git-submodule.sh - Remove trailing / from URL if found

git-submodule.sh - Remove trailing / from URL if found

git clone does not complain if a trailing '/' is included in the origin
URL, but doing so causes resolution of a submodule's URL relative to the
superproject to fail. Trailing /'s are likely when cloning locally using
tab-completion, so the slash may appear in either superproject or
submodule URL. So, ignore the trailing slash if it already exists in
the superproject's URL, and don't record one for the submodule (which
could itself have submodules...).

The problem I'm trying to fix is that a number of folks have
superprojects checked out where the recorded origin URL has a trailing
/, and a submodule has its origin in a directory sitting right next to
the superproject on the server. Thus, we have:

	superproject url = server:/public/super
	submodoule url = server:/public/sub1

However, in the checked out superproject's .git/config

[remote "origin"]
	url = server:/public/super/

and for similar reasons, the submodule has its URL recorded in .gitmodules as
[submodule "sub"]

	path = submodule1
	url = ../sub1/

resolve_relative_url gets the submodule's recorded url as $1, which
the caller retrieved from .gitmodules, and retrieves the superprojects
origin from .git/config. So in this case resolve_relative_url has
that:

	url = ../sub1/
	remoteurl = server:/public/super/

So, without any patch, resolve_relative_url computes the submodule's URL as:

	server:/public/super/sub1/

rather than

	server:/public/sub1

In summary, it is essential that resolve_relative_url strip the
trailing / from the superproject's url before starting, and
beneficial if it assures that the result does not contain
a trailing / as the submodule may itself also be a superproject.

Signed-off-by: Mark Levedahl <mlevedahl@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>