Upgrade to coverage 3.7.1 and have it auto-build itself on first use.

third_party/coverage-3.7.1/doc/cmd.rst

 .. _cmd:
 
 ===========================
 Coverage command line usage
 ===========================
 
 :history: 20090524T134300, brand new docs.
 :history: 20090613T164000, final touches for 3.0
 :history: 20090913T084400, new command line syntax
 :history: 20091004T170700, changes for 3.1
@@ skipping 120 matching lines @@
 
   You asked coverage.py to measure module XXX, but it was never imported by
   your program.
 
 * "No data was collected"
 
   Coverage.py ran your program, but didn't measure any lines as executed.
   This could be because you asked to measure only modules that never ran,
   or for other reasons.
 
+.. _cmd_run_debug:
+
+The ``--debug`` option instructs coverage to log internal details of its
+operation, to help with diagnosing problems.  It takes a comma-separated list
+of options, each indicating a facet of operation to log to stderr:
+
+* ``trace``: print every decision about whether to trace a file or not. For
+  files not being traced, the reason is also given.
+
+* ``config``: before starting, dump all the :ref:`configuration <config>`
+  values.
+
+* ``sys``: before starting, dump all the system and environment information,
+  as with :ref:`coverage debug sys <cmd_debug>`.
+
+* ``dataio``: log when reading or writing any data file.
+
+* ``pid``: annotate all debug output with the process id.
 
 
 .. _cmd_datafile:
 
 Data file
 ---------
 
 Coverage collects execution data in a file called ".coverage".  If need be, you
 can set a new file name with the COVERAGE_FILE environment variable.
 
@@ skipping 10 matching lines @@
 .. _cmd_combining:
 
 Combining data files
 --------------------
 
 If you need to collect coverage data from different machines or processes,
 coverage can combine multiple files into one for reporting. Use the ``-p`` flag
 during execution to append distinguishing information to the .coverage data
 file name.
 
-Once you have created a number of these files, you can copy them all to a single
-directory, and use the **combine** command to combine them into one .coverage
-data file::
+Once you have created a number of these files, you can copy them all to a
+single directory, and use the **combine** command to combine them into one
+.coverage data file::
 
     $ coverage combine
 
 If the different machines run your code from different places in their file
 systems, coverage won't know how to combine the data.  You can tell coverage
 how the different locations correlate with a ``[paths]`` section in your
 configuration file.  See :ref:`config_paths` for details.
 
 If you are collecting and renaming your own data files, you'll need to name
 them properly for **combine** to find them.   It looks for files named after
@@ skipping 117 matching lines @@
 is a data file that is used to speed up reporting the next time.  If you
 generate a new report into the same directory, coverage.py will skip
 generating unchanged pages, making the process faster.
 
 
 .. _cmd_annotation:
 
 Text annotation
 ---------------
 
-The **annotate** command produces a text annotation of your source code.  With a
-``-d`` argument specifying an output directory, each Python file becomes a text
-file in that directory.  Without ``-d``, the files are written into the same
-directories as the original Python files.
+The **annotate** command produces a text annotation of your source code.  With
+a ``-d`` argument specifying an output directory, each Python file becomes a
+text file in that directory.  Without ``-d``, the files are written into the
+same directories as the original Python files.
 
 Coverage status for each line of source is indicated with a character prefix::
 
     > executed
     ! missing (not executed)
     - excluded
 
 For example::
 
       # A simple function, never called with x==1
@@ skipping 31 matching lines @@
 -----------
 
 The **debug** command shows internal information to help diagnose problems.
 If you are reporting a bug about coverage.py, including the output of this
 command can often help::
 
     $ coverage debug sys > please_attach_to_bug_report.txt
 
 Two types of information are available: ``sys`` to show system configuration,
 and ``data`` to show a summary of the collected coverage data.