Gerrit git cl: allow overriding GERRIT_SQUASH_UPLOADS in git config.

git_cl.py

Index: git_cl.py
diff --git a/git_cl.py b/git_cl.py
index b01b7dbbc22388231d829f68ff72ce2d42ee81dd..894567b25c01c005ad28462432a42127e6e71924 100755
--- a/git_cl.py
+++ b/git_cl.py
@@ -2835,8 +2835,11 @@ def LoadCodereviewSettingsFromFile(fileobj):
     RunGit(['config', 'gerrit.host', keyvals['GERRIT_HOST']])
 
   if 'GERRIT_SQUASH_UPLOADS' in keyvals:
-    RunGit(['config', 'gerrit.squash-uploads',
-            keyvals['GERRIT_SQUASH_UPLOADS']])
+    cur = RunGit(['config', '--bool', 'gerrit.squash-uploads'], error_ok=True)
+    if not cur:
+      # Do not override existing setting, if any.

[Sergiy Byelozyorov, 2016/06/15 15:40:45]

imho this comment is confusing, inside if we actually do override existing
setting because no existing one was set. I suggest moving it to the previous
line and changing like this:

if not cur:  # Set the value only if it wasn't set by the user manually.

+      RunGit(['config', 'gerrit.squash-uploads',
+              keyvals['GERRIT_SQUASH_UPLOADS']])
 
   if 'GERRIT_SKIP_ENSURE_AUTHENTICATED' in keyvals:
     RunGit(['config', 'gerrit.skip-ensure-authenticated',