phases: fix `nullid` reference in newheads Spotted by Yuya Nishihara.

beautifygraph: don't warn about busted terminal if HGPLAIN is set This was breaking some automation for users that discovered the extension and turned it on. Differential Revision: https://phab.mercurial-scm.org/D4338

merge with stable

merge: do not delete untracked files silently (issue5962) 37450a122128, 2a774cae3a03, and 656ac240f392 weren't enough to prevent data loss. No unknown "files" weren't deleted before 7a8a16f8ea22, "context: also consider path conflicts when clearing unknown files."

node: correct hex representation of pseudo node ids

merge with stable

perf: fix typo in perfphasesremote()

revlog: fix typo in 'buildtext' name There are no such things as 'deltacomputer._buildtext'. I'm not sure why this code never ran, but we better fix the typo.

revlog: fix pure version of _partialmatch() to include nullid Before this patch, test-issue842.t and a few more tests fail when they try to refer to the null revision by using a "000.." prefix of it (or because they use the "shortest" template function which internally does that). This should have been part of my a3dacabd476b (index: don't allow index[len(index)] to mean nullid, 2018-07-20), but I had forgotten to update another part of the pure code there, so it didn't fail until a1f934573c0b (parsers: adjust pure-python version to mimic a3dacabd476b, 2018-08-09) and 65d5de1169dd (revlog: fix pure nodemap to not access missing index entry, 2018-08-17) fixed the other things I had missed. Differential Revision: https://phab.mercurial-scm.org/D4332

tests: conditionalize color output on abort This broke in afc4ad706f9c. I'm not sure why other aborts don't need to be conditionalized, but `hg help foo` does abort in red for both msys and cmd.exe.