I noted that in BitBucket when your commit log contains a number like #12 this number is linked to the bug number 12.
#12
I found this feature interesting, and
Trac does it as well, of course. It's easily configurable:
_supported_cmds = { 'closed': '_cmdClose', 'fix': '_cmdClose', 'addresses': '_cmdRefs', 're': '_cmdRefs',