With newer versions of Mercurial come newer debug messages which need filtered out.
- In the scenario of Phabricator observing a hosted Mercurial repository which exists on a server in a multi-user environment it's possible that a repository computes branch cache at a tip revision which is not present. When this happens Mercurial will include in the debug output this information. This message indicates that the cache is going to be re-computed. See https://www.mercurial-scm.org/pipermail/mercurial/2014-June/047239.html.
- Likely in some version with added or improved support for pager the debug info seems to indicate when a pager is being invoked for a command. This seems to print out regularly despite piping the stdout.
- If the repository on Phabricator ever had the largefiles extension enabled then some additional details about "updated patterns" will print out.