cmdutil: allow bailifchanged to ignore merging in progress In "commands.update()", "cmdutil.bailifchanged()" isn't used for "abort if the working directory is dirty", because it forcibly examines about merging in progress. "workingctx.dirty()" used in "commands.update()" can't detect changes of largefiles in the working directory without "repo.lfstatus = True" wrapping. This is only reason of "commands.update()" wrapping by largefiles extension. On the other hand, "cmdutil.bailifchanged()" already wrapped by largefiles extension can detect changes of largefiles. This patch is a preparations for replacing "workingctx.dirty()" and raising Abort in "commands.update()" by "cmdutil.bailifchanged()". It can remove redundant "commands.update()" wrapping.