your mce reliably reproduces the magit bug for me, although i have not tried with -q yet. in magit place point on headline b.
- [O] navigation broken in recent maint Samuel Wales
- Re: [O] navigation broken in recent maint Samuel Wales
- Re: [O] navigation broken in recent maint Charles Berry
- Re: [O] navigation broken in recent maint Samuel Wales
- Re: [O] navigation broken in recent maint Samuel Wales
- Re: [O] navigation broken in recent maint Nicolas Richard
- Re: [O] navigation broken in recent maint Samuel Wales