Ubuntu: Jaunty  
Mercurial: 1.3.1  
Access: ssh  (users john and bob)  
File permission:   -rw-rw----  1 john john  129276 May 17 13:28 dirstate  
User: bob  
Command: 'hg st'  
Response:  

**abort: Permission denied: /our/respository/.hg/dirstate**

Obviously mercurial can't let bob see the state because the file it needs to read belongs to me.

So I change the permissions to allow bob to read the file and everything is fine, up until I next try to do something, whence the situations are reversed. Now he owns the file and I can't read it.

So I set up a "committers" group and both john and bob belong to the group, but still mercurial fiddles with the ownership and permissions whenever one or other commits.

How do we configure it so two different logins in the same group can commit to the same repository over ssh?