strip: use bailifchanged() instead of reimplementing it
This also means that we get the standard error messages (see changed
test cases).
Differential Revision: https://phab.mercurial-scm.org/D6535
adding changesets
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added 1 changesets with 4 changes to 4 files
new changesets d326ae2d01ee (1 drafts)
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adding changesets
adding manifests
adding file changes
added 1 changesets with 4 changes to 4 files
new changesets d326ae2d01ee (1 drafts)
4 files updated, 0 files merged, 0 files removed, 0 files unresolved