Mercurial and Bazaar have revision numbers.
Mercurial revision numbers are far too brittle (#3724).
Same Bazaar problem is reported at http://www.redmine.org/boards/2/topics/17587?r=17591#message-17591 .
Redmine generates pseudo revision number for Darcs at source:tags/1.0.2/app/models/repository/darcs.rb#L73 .

If @"closes #issue_number"@ is in commit log, Redmine adds @"Applied in changeset rN"@ at issue journal.

Following two Mercurial repository are full synchronized.
And revision 1 and 2 are different for each other.

If we delete the repository from project setting and re-add another repository,
@"rN"@ points other revision.

$ hg glog
o  changeset:   2:9d5b5b004199
|  tag:         tip
|  parent:      0:0885933ad4f6
|  user:        jsmith 
|  date:        Fri Dec 14 10:24:01 2007 +0100
|  summary:     Added 2 files and modified one.
|
| @  changeset:   1:505aa36abc94
|/   branch:      branch00
|    user:        jsmith 
|    date:        Fri Oct 15 20:09:50 2010 +0900
|    summary:     test.
|
o  changeset:   0:0885933ad4f6
   user:        jsmith 
   date:        Fri Dec 14 10:22:52 2007 +0100
   summary:     Initial import.

$ hg glog
@  changeset:   2:505aa36abc94
|  branch:      branch00
|  tag:         tip
|  parent:      0:0885933ad4f6
|  user:        jsmith 
|  date:        Fri Oct 15 20:09:50 2010 +0900
|  summary:     test.
|
| o  changeset:   1:9d5b5b004199
|/   user:        jsmith 
|    date:        Fri Dec 14 10:24:01 2007 +0100
|    summary:     Added 2 files and modified one.
|
o  changeset:   0:0885933ad4f6
   user:        jsmith 
   date:        Fri Dec 14 10:22:52 2007 +0100
   summary:     Initial import.

I post a patch and a Mercurial image.
This patch master is http://bitbucket.org/yuja/redmine-mq-issue4455/src/d6bc15c54f5d/hg-use-scmid.patch/issue-auto-close.diff .

!auto-close-hg.png!