[git-cache] Fix print log.

Bug: 1372658
Change-Id: I12ab46c8f32b64cf575bff087ed2f82072ebbf8f
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/3949430
Auto-Submit: Joanna Wang <jojwang@chromium.org>
Reviewed-by: Josip Sokcevic <sokcevic@google.com>
Commit-Queue: Josip Sokcevic <sokcevic@google.com>

git_cache.py

@@ -532,7 +532,7 @@ class Mirror(object):
     dest_prefix = '%s/%s' % (self._gs_path, gen_number)
 
     # ls_out lists contents in the format: gs://blah/blah/123...
-    self.print('running "gsutil ls %s":' % self.gs_path)
+    self.print('running "gsutil ls %s":' % self._gs_path)
     ls_code, ls_out, ls_error = gsutil.check_call_with_retries(
         'ls', self._gs_path)
     if ls_code != 0: