patman: force git log commands to not use color

Colored logs confuse patman when analyzing logs.
Add --no-color option in git log commands in case
the default config has color.

Signed-off-by: Albert ARIBAUD <albert.u.boot@aribaud.net>
Acked-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Tom Rini <trini@ti.com>

tools/patman/gitutil.py

@@ -38,7 +38,7 @@ def CountCommitsToBranch():
     Return:
         Number of patches that exist on top of the branch
     """
-    pipe = [['git', 'log', '--oneline', '@{upstream}..'],
+    pipe = [['git', 'log', '--no-color', '--oneline', '@{upstream}..'],
             ['wc', '-l']]
     stdout = command.RunPipe(pipe, capture=True, oneline=True)
     patch_count = int(stdout)