run-tests: pass --with-hg to run-tests.py command used by bisect This makes `run-tests.py -l test-run-tests.t` 23 seconds faster on my laptop. Inside the test, `$ rt --known-good-rev=0 test-bisect.t` took 24.9 seconds before, and 1.2 seconds after. Differential Revision: https://phab.mercurial-scm.org/D576

import-checker: allow relative import a module being checked This would make the checker more friendly for 3rd-party code. For example, In remotefilelog/x.py, it may have: from . import shallowutils That could trigger "relative import of stdlib module" if "remotefilelog" was installed in the system. If the module being checked conflicts with the system module, it makes sense to not treat that module as system module. This patch makes it so. Differential Revision: https://phab.mercurial-scm.org/D552

merge: move some of the logic in batchget() to workingfilectx We will use this logic in two places with in-memory merge. Differential Revision: https://phab.mercurial-scm.org/D444

filemerge: add _restorebackup Differential Revision: https://phab.mercurial-scm.org/D404

filemerge: reduce creation of tempfiles until needed This restricts the creation of temporary files to just `_xmerge`, when we call an external tool. Differential Revision: https://phab.mercurial-scm.org/D403

filemerge: add `_workingpath` This reduces any reliance on `a`. Differential Revision: https://phab.mercurial-scm.org/D401

filemerge: move a util copy call to filectx.write This way a future in-memory-merge context can intercept them. Differential Revision: https://phab.mercurial-scm.org/D400