Create a temporary dir for patch to do its work.

checkout.py

 # coding=utf8
 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 """Manages a project checkout.
 
 Includes support for svn, git-svn and git.
 """
 
 import ConfigParser
@@ skipping 186 matching lines @@
               if os.path.isfile(filepath):
                 raise PatchApplicationFailed(
                     p, 'File exist but was about to be overwriten')
               shutil.copy2(
                   os.path.join(self.project_path, p.source_filename), filepath)
               stdout.append('Copied %s -> %s' % (p.source_filename, p.filename))
             if p.diff_hunks:
               cmd = ['patch', '-u', '--binary', '-p%s' % p.patchlevel]
               if verbose:
                 cmd.append('--verbose')
-              stdout.append(
-                  subprocess2.check_output(
-                      cmd,
-                      stdin=p.get(False),
-                      stderr=subprocess2.STDOUT,
-                      cwd=self.project_path,
-                      timeout=GLOBAL_TIMEOUT))
+              env = os.environ.copy()
+              env['TMPDIR'] = tempfile.mkdtemp(prefix='crpatch')
+              try:
+                stdout.append(
+                    subprocess2.check_output(
+                        cmd,
+                        stdin=p.get(False),
+                        stderr=subprocess2.STDOUT,
+                        cwd=self.project_path,
+                        timeout=GLOBAL_TIMEOUT,
+                        env=env))
+              finally:
+                shutil.rmtree(env['TMPDIR'])
             elif p.is_new and not os.path.exists(filepath):
               # There is only a header. Just create the file.
               open(filepath, 'w').close()
               stdout.append('Created an empty file.')
         for post in post_processors:
           post(self, p)
         if verbose:
           print p.filename
           print align_stdout(stdout)
       except OSError, e:
@@ skipping 169 matching lines @@
                     ['copy', p.source_filename, p.filename]))
               stdout.append('Copied %s -> %s' % (p.source_filename, p.filename))
             if p.diff_hunks:
               cmd = [
                 'patch',
                 '-p%s' % p.patchlevel,
                 '--forward',
                 '--force',
                 '--no-backup-if-mismatch',
               ]
-              stdout.append(
-                  subprocess2.check_output(
-                    cmd,
-                    stdin=p.get(False),
-                    cwd=self.project_path,
-                    timeout=GLOBAL_TIMEOUT))
+              env = os.environ.copy()
+              env['TMPDIR'] = tempfile.mkdtemp(prefix='crpatch')
+              try:
+                stdout.append(
+                    subprocess2.check_output(
+                      cmd,
+                      stdin=p.get(False),
+                      cwd=self.project_path,
+                      timeout=GLOBAL_TIMEOUT,
+                      env=env))
+              finally:
+                shutil.rmtree(env['TMPDIR'])
+
             elif p.is_new and not os.path.exists(filepath):
               # There is only a header. Just create the file if it doesn't
               # exist.
               open(filepath, 'w').close()
               stdout.append('Created an empty file.')
           if p.is_new and not p.source_filename:
             # Do not run it if p.source_filename is defined, since svn copy was
             # using above.
             stdout.append(
                 self._check_output_svn(
@@ skipping 332 matching lines @@
   def revisions(self, rev1, rev2):
     return self.checkout.revisions(rev1, rev2)
 
   @property
   def project_name(self):
     return self.checkout.project_name
 
   @property
   def project_path(self):
     return self.checkout.project_path