histedit: properly handle --continue on empty fold When all changes from the fold have been dropped, the --continue code was confused. This changeset handles this case. The test for this case existed but was broken.

histedit-test: replace obscure python script by a plain file One of the tests uses a python script to edit the histedit commands on the fly. It was hard to read and likely to break. This is replaced by a plain command file. Doing so made me discover that the python script is incorrect. The "+6" regexp never matched because the revision number is wrong. This error is kept in the replacement for now. Fixing the histedit command triggers a traceback in histedit. A later changeset will fix the error and restore the intended test.

test: improve documentation of some histedit tests Each test section is clearly separated from the others and gains some helpful documentation.

test: use a lighter log style in histedit test The default log displays a log of information that is useless for histedit tests. Having a cleaner log help readability of those tests a lot. This does not change anything to the test semantic.

subrepo: add regression test for issue3870

subrepo: clone of git sub-repository creates incorrect git branch (issue3870) Mercurial handles git subrepos by incorrect way. If the mercurial repo has a git sub-repo and somebody started a new branch in the subrepo and push it into git, the next one who will clone the whole repo will get incorrect branch name in the git subrepo.