Save code now on staging [1] (or production [2]) for mercurial repositories triggers the following issues.

I did not investigate [3] further than that but on fresh staging (all deps up-to-date),
triggering mercurial repositories save code now made sentry raise this issue (marked resolved
as regression).

[1] https://sentry.softwareheritage.org/share/issue/c5622cacc16141fcaace2a61eab1b3b1/
[2] https://sentry.softwareheritage.org/share/issue/114c53a2e1104ba987d0771f846a78ad/
[3] might be it's the loader altogether which is broken, i did not check