Useless hunks dividers in diff view between contiguous hunks
Summary
When viewing a diff, contiguous hunks are not merged in the UI, resulting in confusing (and useless) "Show 20 lines" etc. buttons between them.
Steps to reproduce
Go to any diff with contiguous hunks like mercurial/mercurial-devel!138 (0dc5d69c) and observe.
What is the current bug behavior?
The "show X lines..." divider is shown between contiguous hunks
What is the expected correct behavior?
Contiguous hunks should be detected and the divider should only be present when useful (including after using it to expand between two non-contiguous hunks that then become contiguous).
Seen on foss.heptapod.net (but very likely still broken in Heptapod dev itself).
Heptapod 0.31.1 (GitLab CE 14.9.5) Mercurial 6.1.3 / Python 3.9.13 / hg-evolve 10.5.1