Cherry-pick bot does not correctly parse commit message when querying changes from gerrit

The Pick-to: commit message parser in cherry-pick bot uses a regex to ensure that the footer sits at the beginning of a line, but it fails to parse this correctly when parsing commit messages returned as a result of a REST query to gerrit.

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This appears to be due to the rest responses from gerrit being encoded in plaintext, and newline characters "\n" are interpreted as string literals. This needs to be corrected for, and the bot's parser regex updated to look for either start of line with "^" or the string literal "\n".

This actually appears to be due to using invalid functions to determine the length and content of the set of branches returned by the parser.