Second take at handling users with locally overridden diff-cmds.

The first take at https://chromiumcodereview.appspot.com/14130006 tried to pass
"--diff-cmd diff", which doesn't work for e.g. Windows cmd users who don't have
a "diff" executable installed.

This take instead passes the "--internal-diff" switch which tells svn to ignore
any diff-cmd set locally and use its internal diff engine at all times.

While implementing this I found that the existing code tried to work around this
problem in a different way, by setting up a bogus config dir.  Since that
doesn't seem to work for me, and shouldn't be necessary with this patch anyway,
removed that code.

Review URL: https://chromiumcodereview.appspot.com/14050007

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@194990 0039d316-1c4b-4281-b951-d872f2087c98

scm.py

@@ -10,7 +10,6 @@ import logging
 import os
 import re
 import sys
-import tempfile
 import time
 from xml.etree import ElementTree
 
@@ -780,30 +779,19 @@ class SVN(object):
     expected relative path.
     full_move means that move or copy operations should completely recreate the
     files, usually in the prospect to apply the patch for a try job."""
-    # If the user specified a custom diff command in their svn config file,
-    # then it'll be used when we do svn diff, which we don't want to happen
-    # since we want the unified diff.  Using --diff-cmd=diff doesn't always
-    # work, since they can have another diff executable in their path that
-    # gives different line endings.  So we use a bogus temp directory as the
-    # config directory, which gets around these problems.
-    bogus_dir = tempfile.mkdtemp()
-    try:
     # Use "svn info" output instead of os.path.isdir because the latter fails
     # when the file is deleted.
     return SVN._DiffItemInternal(
         filename,
         cwd,
         SVN.CaptureLocalInfo([filename], cwd),
-          bogus_dir,
         full_move,
         revision)
-    finally:
-      gclient_utils.RemoveDirectory(bogus_dir)
 
   @staticmethod
-  def _DiffItemInternal(filename, cwd, info, bogus_dir, full_move, revision):
+  def _DiffItemInternal(filename, cwd, info, full_move, revision):
     """Grabs the diff data."""
-    command = ["diff", "--config-dir", bogus_dir, filename]
+    command = ["diff", "--internal-diff", filename]
     if revision:
       command.extend(['--revision', revision])
     data = None
@@ -871,14 +859,6 @@ class SVN(object):
       if os.path.normcase(path).startswith(root):
         return path[len(root):]
       return path
-    # If the user specified a custom diff command in their svn config file,
-    # then it'll be used when we do svn diff, which we don't want to happen
-    # since we want the unified diff.  Using --diff-cmd=diff doesn't always
-    # work, since they can have another diff executable in their path that
-    # gives different line endings.  So we use a bogus temp directory as the
-    # config directory, which gets around these problems.
-    bogus_dir = tempfile.mkdtemp()
-    try:
     # Cleanup filenames
     filenames = [RelativePath(f, root) for f in filenames]
     # Get information about the modified items (files and directories)
@@ -915,13 +895,13 @@ class SVN(object):
             # revision the file was deleted.
             srcinfo = {'Revision': rev}
           if (srcinfo.get('Revision') != rev and
-                SVN.Capture(['diff', '-r', '%d:head' % rev, srcurl], cwd)):
+              SVN.Capture(['diff', '--internal-diff', '-r', '%d:head' % rev,
+                           srcurl], cwd)):
             metaheaders.append("#$ svn cp -r %d %s %s "
                                "### WARNING: note non-trunk copy\n" %
                                (rev, src, filename))
           else:
-              metaheaders.append("#$ cp %s %s\n" % (src,
-                                                    filename))
+            metaheaders.append("#$ cp %s %s\n" % (src, filename))
 
       if metaheaders:
         diffs.append("### BEGIN SVN COPY METADATA\n")
@@ -929,8 +909,8 @@ class SVN(object):
         diffs.append("### END SVN COPY METADATA\n")
     # Now ready to do the actual diff.
     for filename in sorted(data.iterkeys()):
-        diffs.append(SVN._DiffItemInternal(
-            filename, cwd, data[filename], bogus_dir, full_move, revision))
+      diffs.append(SVN._DiffItemInternal(filename, cwd, data[filename],
+                                         full_move, revision))
     # Use StringIO since it can be messy when diffing a directory move with
     # full_move=True.
     buf = cStringIO.StringIO()
@@ -939,8 +919,6 @@ class SVN(object):
     result = buf.getvalue()
     buf.close()
     return result
-    finally:
-      gclient_utils.RemoveDirectory(bogus_dir)
 
   @staticmethod
   def GetEmail(cwd):