Cannot push to gitlab via https

Created originally on Bitbucket by cbillington (Chris Billington)

I'm using the latest bitbucket version of hg-git, mercurial 4.8.2, and dulwich 0.19.11.

I can't seem to push to gitlab with https:

[bilbo:clones]$ hg clone git+https://gitlab.com/chrisjbillington/importlib_metadata/ importlib_metadata_hggit
importing git objects into hg
updating to branch default
29 files updated, 0 files merged, 0 files removed, 0 files unresolved
[bilbo:clones]$ cd importlib_metadata_hggit/
[bilbo:importlib_metadata_hggit]$ hg push
pushing to git+https://gitlab.com/chrisjbillington/importlib_metadata/
abort: git remote error: unexpected http resp 401 for https://gitlab.com/chrisjbillington/importlib_metadata/info/refs?service=git-receive-pack

I am not sure if I am doing something wrong here, please let me know if I'm just being naive about something, I was under the impression this should work.

In case it is relevant, my .hgrc has:

[auth]
gitlab.schemes = http https
gitlab.prefix = gitlab.com
gitlab.username = chrisjbillington

Which I copied from last time I used hg-git with github a number of years ago. However if I remove these lines I still get the same error when I push.