[hg] removing dead subrepository

On migrating my hg-repositories to git I found one project with subrepositories which were already deleted.

Switching branches resulted in

abort: HTTP Error 404: Not Found

 The internet came up with solutions like:

• https://stackoverflow.com/questions/7616950/cloning-a-mercurial-repository-hgsub-refers-to-a-dead-external-subrepo
• https://markmail.org/thread/ktxd2rsm7avkexzr#query:+page:1+mid:oz6s4qrbatszfoqf+state:results
• https://stackoverflow.com/questions/7946320/how-to-fix-a-mercurial-repo-that-fails-updating-because-points-to-missing-revisi
• https://www.mercurial-scm.org/pipermail/mercurial/2018-June/050913.html

But I couldn't get it to work easily…

What I did finally:
Clone the branch into a new folder

$ hg clone -U -b BRANCH https://bitbucket.org/USER/PROJECT PROJCET-BRANCH

-U will not make an update, which will result in an nearly empty folder. Basically nothing specific is checked out.

Next is getting all files except the .hgsub file, creating that file as empty, setting options, "going" to the branch, committing the change, and pushing it:

$ hg revert -a -r BRANCH -X .hgsub

$ cat /dev/null > .hgsub

$ hg debugrebuildstate -r BRANCH

$ hg debugsetparents BRANCH

$ hg update BRANCH

$ hg branch BRANCH

$ hg ci -m "no subrepos"

$ hg push