filemerge: migrate to scmutil.backuppath() Differential Revision: https://phab.mercurial-scm.org/D5856

mq: migrate to scmutil.backuppath() Differential Revision: https://phab.mercurial-scm.org/D5855

largefiles: migrate to scmutil.backuppath() It seems unnecessary to convert the paths here back to repo-relative paths, but I'll leave that for someone else to clean up. Differential Revision: https://phab.mercurial-scm.org/D5854

revert: migrate to scmutil.backuppath() Differential Revision: https://phab.mercurial-scm.org/D5853

shelve: fix broken backup of conflicting untracked file Differential Revision: https://phab.mercurial-scm.org/D5852

scmutil: introduce a new backuppath() to replace origpath() Unlike most functions in our codebase, origpath() takes a path that is relative to cwd. This commit introduces a replacement for origpath(). The new function takes a path that is relative to the repo root. There is a lot of duplication between the two, but I intend to remove origpath() within the next few commits, so it won't be a maintenance burden. origpath() is also a little weird in that it returns either a a cwd-relative path or an absolute path. It needs to be able to return a path outside the repo, so it makes sense that it can return an absolute path. However, it would be simpler to always return an absolute path. The new function does that. Differential Revision: https://phab.mercurial-scm.org/D5851

tests: demonstrate broken unshelve when backing up untracked file Differential Revision: https://phab.mercurial-scm.org/D5850

subrepo: always show relative path to .orig backup Same as previous commit, but for subrepo. Differential Revision: https://phab.mercurial-scm.org/D5873