If you're trying to clone a repo via ssh (git@server:foo.git) that has a subrepo reference for http://server/bar.git then subrepos are recognised correctly but then a password prompt is provided with fixed user git that was ok for SSH but is not ok for HTTP.

1. Please check that user of another URI is not used in wrong context
2. check that a URI is not assumed as username (try to enter ssh+git://git@server:foo.git then you're prompted for ssh+git's password ;/
3. check routing if login for submodules fails. It seems to, there are never ending git fork processes that are not canceled if canceling the username / password dialog! So SourceTree got hangup!