patman: Use the full commit hash for 'git checkout'

Even with the initial 8 characeters of the hash we will sometimes get a
collision. Use the full hash.

Signed-off-by: Simon Glass <sjg@chromium.org>

tools/buildman/control.py

@@ -70,7 +70,7 @@ def ShowActions(series, why_selected, boards_selected, builder, options):
     if commits:
         for upto in range(0, len(series.commits), options.step):
             commit = series.commits[upto]
-            print '   ', col.Color(col.YELLOW, commit.hash, bright=False),
+            print '   ', col.Color(col.YELLOW, commit.hash[:8], bright=False),
             print commit.subject
     print
     for arg in why_selected: