Allow --3way to be passed to `git apply` via `git cl patch`.

git_cl.py

Index: git_cl.py
diff --git a/git_cl.py b/git_cl.py
index 4dfb609eb42ad9adda546b18fb2c00a6262af0f2..c03b5a85eed8590d2e9e21a25aa767f33ee1a622 100755
--- a/git_cl.py
+++ b/git_cl.py
@@ -8,6 +8,7 @@
 """A git-command for integrating reviews on Rietveld."""
 
 import difflib
+from distutils.version import LooseVersion

[M-A Ruel, 2013/07/09 13:27:15]

I don't think this exists on Windows.

[tapted, 2013/07/10 01:11:52]

All my tests seem happy. I think this is just part of the python standard
library, since 1998 (aka forever). The file history is just whitepsace and
comment tweaks -
http://hg.python.org/cpython/log/b44749cee660/Lib/distutils/version.py

Tested with Python 2.6.2 in cmd.exe . I had to install unixutils and put it in
my path because `git cl patch` runs things through `sed`. There's even a
convenient conflict landed in git_cl.py the last 24 hours to see the 'old'
behaviour.

D:\src\depot_tools>python --version
Python 2.6.2

D:\src\depot_tools>where python
D:\src\depot_tools\python.bat
C:\python_26_amd64\files\python.exe

D:\src\depot_tools>python git_cl.py patch 16211005
Loaded authentication cookies from C:\Users\tapted/.codereview_upload_cookies
error: patch failed: git_cl.py:1757
error: git_cl.py: patch does not apply
Failed to apply the patch

/* rebase at 18966004 */

D:\src\depot_tools>python git_cl.py patch 18966004
Loaded authentication cookies from C:\Users\tapted/.codereview_upload_cookies
Committed patch locally.

D:\src\depot_tools>git cl patch 18966004
Loaded authentication cookies from C:\Users\tapted/.codereview_upload_cookies
error: patch failed: git_cl.py:8
Falling back to three-way merge...
Applied patch to 'git_cl.py' cleanly.
Command "git commit -m patch from issue 18966004" failed.
# On branch master
# Your branch is ahead of 'origin/master' by 1 commit.
#
nothing to commit, working directory clean

 import json
 import logging
 import optparse
@@ -84,6 +85,13 @@ def RunGitWithCode(args):
     return 1, ''
 
 
+def IsGitVersionAtLeast(min_version):
+  PREFIX='git version '
+  version = RunGit(['--version']).strip()
+  return (version.startswith(PREFIX) and
+      LooseVersion(version[len(PREFIX):]) >= LooseVersion(min_version))
+
+
 def usage(more):
   def hook(fn):
     fn.usage_more = more
@@ -1699,7 +1707,8 @@ def CMDpatch(parser, args):
   parser.add_option('-f', action='store_true', dest='force',
                     help='with -b, clobber any existing branch')
   parser.add_option('--reject', action='store_true', dest='reject',
-                    help='allow failed patches and spew .rej files')
+                    help='failed patches spew .rej files rather than '
+                        'attempting a 3-way merge')
   parser.add_option('-n', '--no-commit', action='store_true', dest='nocommit',
                     help="don't commit after patch applies")
   (options, args) = parser.parse_args(args)
@@ -1757,6 +1766,8 @@ def CMDpatch(parser, args):
   cmd = ['git', '--no-pager', 'apply', '--index', '-p0']
   if options.reject:
     cmd.append('--reject')
+  elif IsGitVersionAtLeast('1.7.12'):
+    cmd.append('--3way')
   try:
     subprocess2.check_call(cmd, stdin=patch_data, stdout=subprocess2.VOID)
   except subprocess2.CalledProcessError: