Poll manage projects config fetches.

Retry every 2 seconds when fetching the refs/meta/config ref from gerrit
on new projects.

Change-Id: I5942396fb8dbede167f86e48aff6e8ec17eee282
diff --git a/jeepyb/cmd/manage_projects.py b/jeepyb/cmd/manage_projects.py
index 372e2ed..230e274 100644
--- a/jeepyb/cmd/manage_projects.py
+++ b/jeepyb/cmd/manage_projects.py
@@ -128,8 +128,19 @@
 
 
 def fetch_config(project, remote_url, repo_path, env={}):
-    status = git_command(repo_path, "fetch %s +refs/meta/config:"
-                         "refs/remotes/gerrit-meta/config" % remote_url, env)
+    # Poll for refs/meta/config as gerrit may not have written it out for
+    # us yet.
+    for x in range(10):
+        status = git_command(repo_path, "fetch %s +refs/meta/config:"
+                             "refs/remotes/gerrit-meta/config" %
+                             remote_url, env)
+        if status == 0:
+            break
+        else:
+            log.debug("Failed to fetch refs/meta/config for project: %s" %
+                      project)
+            time.sleep(2)
+
     if status != 0:
         log.error("Failed to fetch refs/meta/config for project: %s" % project)
         return False