rebaseline.py: make builder names copy-pastable from --help output

tools/rebaseline.py

Index: tools/rebaseline.py
===================================================================
--- tools/rebaseline.py	(revision 11346)
+++ tools/rebaseline.py	(working copy)
@@ -329,7 +329,10 @@
 
 # main...
 
-parser = argparse.ArgumentParser()
+parser = argparse.ArgumentParser(
+    formatter_class=argparse.RawDescriptionHelpFormatter,
+    epilog='Here is the full set of builders we know about:' +

[epoger, 2013/09/18 14:46:16]

Unfortunately, if we want ANY control over the formatting for the argparse
argument help, we become responsible for ALL formatting of the help.  See
http://stackoverflow.com/questions/3853722/python-argparse-how-to-insert-newl...
for details.

So how about this compromise, listing the builder names at the bottom of the
help output?  It looks like this:

$ tools/rebaseline.py --help
usage: rebaseline.py [-h] [--actuals-base-url ACTUALS_BASE_URL]
                     [--actuals-filename ACTUALS_FILENAME] [--add-new]
                     [--bugs BUG [BUG ...]] [--builders BUILDER [BUILDER ...]]
                     [--configs CONFIG [CONFIG ...]]
                     [--expectations-filename EXPECTATIONS_FILENAME]
                     [--expectations-filename-output
EXPECTATIONS_FILENAME_OUTPUT]
                     [--expectations-root EXPECTATIONS_ROOT]
                     [--keep-going-on-failure] [--notes NOTES]
                     [--tests TEST [TEST ...]] [--unreviewed] [--from-trybot]

optional arguments:
  -h, --help            show this help message and exit
  --actuals-base-url ACTUALS_BASE_URL
                        base URL from which to read files containing JSON
                        summaries of actual GM results; defaults to http
                        ://skia-autogen.googlecode.com/svn/gm-actual
  --actuals-filename ACTUALS_FILENAME
                        filename (within builder-specific subdirectories of
                        ACTUALS_BASE_URL) to read a summary of results from;
                        defaults to actual-results.json
  --add-new             in addition to the standard behavior of updating
                        expectations for failing tests, add expectations for
                        tests which don't have expectations yet.
  --bugs BUG [BUG ...]  Skia bug numbers (under
                        https://code.google.com/p/skia/issues/list ) which
                        pertain to this set of rebaselines.
  --builders BUILDER [BUILDER ...]
                        which platforms to rebaseline; if unspecified,
                        rebaseline all known platforms (see below for a list)
  --configs CONFIG [CONFIG ...]
                        which configurations to rebaseline, e.g. "--configs
                        565 8888", as a filter over the full set of results in
                        ACTUALS_FILENAME; if unspecified, rebaseline *all*
                        configs that are available.
  --expectations-filename EXPECTATIONS_FILENAME
                        filename (under EXPECTATIONS_ROOT) to read current
                        expectations from, and to write new expectations into
                        (unless a separate EXPECTATIONS_FILENAME_OUTPUT has
                        been specified); defaults to expected-results.json
  --expectations-filename-output EXPECTATIONS_FILENAME_OUTPUT
                        filename (under EXPECTATIONS_ROOT) to write updated
                        expectations into; by default, overwrites the input
                        file (EXPECTATIONS_FILENAME)
  --expectations-root EXPECTATIONS_ROOT
                        root of expectations directory to update-- should
                        contain one or more builder subdirectories. Defaults
                        to expectations/gm
  --keep-going-on-failure
                        instead of halting at the first error encountered,
                        keep going and rebaseline as many tests as possible,
                        and then report the full set of errors at the end
  --notes NOTES         free-form text notes to add to all updated
                        expectations
  --tests TEST [TEST ...]
                        which tests to rebaseline, e.g. "--tests aaclip
                        bigmatrix", as a filter over the full set of results
                        in ACTUALS_FILENAME; if unspecified, rebaseline *all*
                        tests that are available.
  --unreviewed          mark all expectations modified by this run as
                        "reviewed-by-human": False
  --from-trybot         pull the actual-results.json file from the
                        corresponding trybot, rather than the main builder

Here is the full set of builders we know about:
    Test-Android-GalaxyNexus-SGX540-Arm7-Debug
    Test-Android-GalaxyNexus-SGX540-Arm7-Release
    Test-Android-IntelRhb-SGX544-x86-Debug
    Test-Android-IntelRhb-SGX544-x86-Release
    Test-Android-Nexus10-MaliT604-Arm7-Debug
    Test-Android-Nexus10-MaliT604-Arm7-Release
    Test-Android-Nexus4-Adreno320-Arm7-Debug
    Test-Android-Nexus4-Adreno320-Arm7-Release
    Test-Android-Nexus7-Tegra3-Arm7-Debug
    Test-Android-Nexus7-Tegra3-Arm7-Release
    Test-Android-NexusS-SGX540-Arm7-Debug
    Test-Android-NexusS-SGX540-Arm7-Release
    Test-Android-Xoom-Tegra2-Arm7-Debug
    Test-Android-Xoom-Tegra2-Arm7-Release
    Test-ChromeOS-Alex-GMA3150-x86-Debug
    Test-ChromeOS-Alex-GMA3150-x86-Release
    Test-ChromeOS-Daisy-MaliT604-Arm7-Debug
    Test-ChromeOS-Daisy-MaliT604-Arm7-Release
    Test-ChromeOS-Link-HD4000-x86_64-Debug
    Test-ChromeOS-Link-HD4000-x86_64-Release
    Test-Mac10.6-MacMini4.1-GeForce320M-x86-Debug
    Test-Mac10.6-MacMini4.1-GeForce320M-x86-Release
    Test-Mac10.6-MacMini4.1-GeForce320M-x86_64-Debug
    Test-Mac10.6-MacMini4.1-GeForce320M-x86_64-Release
    Test-Mac10.7-MacMini4.1-GeForce320M-x86-Debug
    Test-Mac10.7-MacMini4.1-GeForce320M-x86-Release
    Test-Mac10.7-MacMini4.1-GeForce320M-x86_64-Debug
    Test-Mac10.7-MacMini4.1-GeForce320M-x86_64-Release
    Test-Mac10.8-MacMini4.1-GeForce320M-x86-Debug
    Test-Mac10.8-MacMini4.1-GeForce320M-x86-Release
    Test-Mac10.8-MacMini4.1-GeForce320M-x86_64-Debug
    Test-Mac10.8-MacMini4.1-GeForce320M-x86_64-Release
    Test-Ubuntu12-ShuttleA-ATI5770-x86-Debug
    Test-Ubuntu12-ShuttleA-ATI5770-x86-Release
    Test-Ubuntu12-ShuttleA-ATI5770-x86_64-Debug
    Test-Ubuntu12-ShuttleA-ATI5770-x86_64-Release
    Test-Ubuntu12-ShuttleA-HD2000-x86_64-Release-Valgrind
    Test-Ubuntu12-ShuttleA-NoGPU-x86_64-Debug
    Test-Ubuntu13-ShuttleA-HD2000-x86_64-Debug-ASAN
    Test-Win7-ShuttleA-HD2000-x86-Debug
    Test-Win7-ShuttleA-HD2000-x86-Debug-ANGLE
    Test-Win7-ShuttleA-HD2000-x86-Debug-DirectWrite
    Test-Win7-ShuttleA-HD2000-x86-Release
    Test-Win7-ShuttleA-HD2000-x86-Release-ANGLE
    Test-Win7-ShuttleA-HD2000-x86-Release-DirectWrite
    Test-Win7-ShuttleA-HD2000-x86_64-Debug
    Test-Win7-ShuttleA-HD2000-x86_64-Release

+           '\n    '.join([''] + sorted(TEST_BUILDERS)))
 parser.add_argument('--actuals-base-url',
                     help=('base URL from which to read files containing JSON '
                           'summaries of actual GM results; defaults to '
@@ -351,8 +354,8 @@
                           'pertain to this set of rebaselines.'))
 parser.add_argument('--builders', metavar='BUILDER', nargs='+',
                     help=('which platforms to rebaseline; '
-                          'if unspecified, rebaseline all platforms, same as '
-                          '"--builders %s"' % ' '.join(sorted(TEST_BUILDERS))))
+                          'if unspecified, rebaseline all known platforms '
+                          '(see below for a list)'))
 # TODO(epoger): Add test that exercises --configs argument.
 parser.add_argument('--configs', metavar='CONFIG', nargs='+',
                     help=('which configurations to rebaseline, e.g. '