Use core.quotePath=false for more git diffs

This includes a minor refactor so that some gclient_scm methods
can all share the same core.quotePath specifier.

R=iannucci

Bug: 792302
Change-Id: Iaadf190f5c0666787cf7c2ccda88d6dba9aace9b
Reviewed-on: https://chromium-review.googlesource.com/823131
Reviewed-by: Robbie Iannucci <iannucci@chromium.org>
Commit-Queue: Aaron Gable <agable@chromium.org>
diff --git a/tests/gclient_scm_test.py b/tests/gclient_scm_test.py
index 5c6bf4c..71b5f54 100755
--- a/tests/gclient_scm_test.py
+++ b/tests/gclient_scm_test.py
@@ -340,7 +340,7 @@
     scm.status(options, self.args, file_list)
     self.assertEquals(file_list, [file_path])
     self.checkstdout(
-        ('\n________ running \'git diff --name-status '
+        ('\n________ running \'git -c core.quotePath=false diff --name-status '
          '069c602044c5388d2d15c3f875b057c852003458\' in \'%s\'\nM\ta\n') %
             join(self.root_dir, '.'))
 
@@ -360,7 +360,7 @@
     expected_file_list = [join(self.base_path, x) for x in ['a', 'b']]
     self.assertEquals(sorted(file_list), expected_file_list)
     self.checkstdout(
-        ('\n________ running \'git diff --name-status '
+        ('\n________ running \'git -c core.quotePath=false diff --name-status '
          '069c602044c5388d2d15c3f875b057c852003458\' in \'%s\'\nM\ta\nM\tb\n') %
             join(self.root_dir, '.'))