Secure revisions report a confusing "A generic error occurred in the code review bot"

[Standard8]

We posted a secure revision to phabricator with various updates.

Actual Results

• For each update there's an indication that Harbormaster failed remote builds in...
• There's a message at the top of the page that states "A generic error occurred in the code review bot"
• The "Analysis Task" shows as failed.
• Looking at the "Analysis Task" logs, shows there's a line which states Exception: Cannot process private builds

Expected Results

• The build should be flagged as warning, not a failure.
• Code review bot should produce a nice warning message that states are analysis tasks are not run because it is a secure revision.
• It probably doesn't need to notify via email, since this is a permanent state and there's nothing that can be done about it.