git-svn dcommit ignores --username if there are cached credentials

Hi,

I am new to Git and using 1.6.6. I'm very interested by using it to mirror SVN 
repositories. But I am running into troubles with the way git-svn handles SVN 
credentials. 

For one SVN I use I have some cached credentials that have only very restricted 
write access. With svn command, I am using --username for every commit and this 
cached credential is just ignored: I'm asked for a password.

With git-svn, I use --username at init/fetch but during dcommit --username is 
ignored becaused of the cached credential. I can see in SVN logs that the 
cached credential (which doesn't have the right to commit the mods I made) has 
been used instead of the one specified during fetch. If I removed the cached 
credential, the username specified with --username is taken into account (I'm 
asked a password for it and it works) and if I ommit the --username, the one 
specified at fetch time is used.

IMO, looks like a bug... Thanks in advance for any comment.

Cheers,

Michel