Submodule revision links are broken in source browser (BB-7244)

When submodules are displayed in a repository, the link to the root of the submodule repository works, but the specific revision goes to an incorrect url. It appears to be missing the project name. For example a subrepos to https://github.com/ShareKit/ShareKit, the link in brackets next to it goes to https://github.com/ShareKit/commit/43f8432ed7fda4f988be5d90d9c832880884ac13 rather than the correct https://github.com/ShareKit/ShareKit/commit/43f8432ed7fda4f988be5d90d9c832880884ac13.

This also applies to BitBucket links as well as GitHub ones, but I am not sure of the correct url for changesets in order to give a good example. It appears to be missing the repository name as well.