py3: use '%d' for integers instead of '%s' Differential Revision: https://phab.mercurial-scm.org/D5285

py3: add 9 new passing tests caught by buildbot Differential Revision: https://phab.mercurial-scm.org/D5284

branch: allow changing branch of merge commits with --rev Tests show that changing branch of merge commits works fine with evolution and without, so let's allow it. Other safeguards should prevent users from shooting themselves in the foot.

lfs: ensure that the return of urlopener.open() is closed No problem observed, just an oversight noticed while reading documentation.

changegroup: avoid instantiating storage if we are not using it Differential Revision: https://phab.mercurial-scm.org/D5280

http: allow 'auth.prefix' to have a username consistent with the URI It may be a little weird to put a username in the prefix, but the documentation doesn't disallow it, and silently disallowing it has caused confusion[1]. The username must match what is passed in (which seems to be from the URI via a circuitous route), as well as 'auth.username' if it was specified. I thought about printing a warning for a mismatch, but we already don't print a warning if the 'auth.username' and URI username don't match. This change allows the first and second last new test cases to work as expected. It looks like this would have been a problem since at least 0593e8f81c71. [1] https://www.mercurial-scm.org/pipermail/mercurial/2018-November/051069.html

lfs: make the exception messages consistent I don't love that it repeats 'HTTP Error' in an already long message, but I doubt that we should assume that it will always say that on the original exception message.