dispatch: extract stub function to peek boolean command option We should at least stop parsing at "--". The 'name' argument is passed for future extension.

dispatch: do not drop unpaired argument at _earlygetopt() Before, "hg log -R" just worked.

amend: update .hgsubstate before committing a memctx (issue5677) This is a minimal copy of localrepo.commit(). As the current amend() function heavily depends on the wctx API, it wasn't easy to port it to use a separate status tuple. So for now, wctx._status is updated in-place.

subrepo: extract preprocess of repo.commit() to free function No code change other than extracting a function. Maybe we should stop mutating the status argument, but that's out of the scope of stable changes.

tests: demonstrate that .hgsubstate isn't updated on amend Loosely based on test-amend.t and test-subrepo.t

amend: do not drop missing files (issue5732) samefile() can be wrong since wctx.manifest() does not include missing files, whereas missing files should be preserved on commit.