lfs: register the flag processors per repository Previously, enabling the extension for any repo in commandserver or hgweb would enable the flags on all repos. Since localrepo.resolverevlogstorevfsoptions() is called so early, the check to see if the extension is enabled on the repo (which hasn't been instantiated yet) is a bit awkward. But I don't see a better way.

revlog: allow flag processors to be applied via store options This allows flag processors to be registered to specific repos in an extension by wrapping localrepo.resolverevlogstorevfsoptions(). I wanted to add the processors via a function on localrepo, but some of the places where the processors are globally registered don't have a repository available. This makes targeting specific repos in the wrapper awkward, but still manageable.

py3: use str to query registry values on Windows This blew up launching any command if extdiff processed a tool with a regkey config.

py3: convert "usage" literal to bytes Here _() is practically an identity function, but we shouldn't pass in unicode to _().

churn: remove redundant round() To my surprise, the int() is required. Spotted by Mads when he reviewed D5063. Thanks! Differential Revision: https://phab.mercurial-scm.org/D5086

py3: use py3 as the test tag, dropping the k Differential Revision: https://phab.mercurial-scm.org/D5079