Nested subrepositories (BB-1004)

A typical and quite canonical setup using subrepositories is to have the source repository embedded directly into the main repository with a {{

{.hgsub}

}} file like this:
{{{
libs/foo = libs/foo
libs/bar = libs/bar
}}}

You cannot push such a repository to Bitbucket since it would require that you can clone from URLs of the form
{{{
http://bitbucket.org/<user>/<main>/
http://bitbucket.org/<user>/<main>/libs/libfoo
http://bitbucket.org/<user>/<main>/libs/libbar
}}}

Sniffing the user agent should make it possible to support this for {{

{hg clone}

}}. However, it is a good question how Bitbucket should behave when people use their normal browser, i.e., where do they go to see the {{

{libs/libfoo}

}} repository?