Allowing push --dry-run through fetch url

[Mike Hommey <mh@glandium.org>]

Hi,

I am currently considering, when I'll get some time, to dive in the git
push code to allow push --dry-run without the rights to push.

We currently have two remote configuration items for urls:
remote.<name>.url and remote.<name>.pushurl. The latter is used when
pushing and the former when pulling/fetching.

The typical use of both at the same time is to put an authenticated
value for pushurl (ssh://, for example) and an anonymous one (git://,
for example) for url.

What has been annoying me lately is that git push --dry-run asks me
for the ssh key or password. I know I could be using an ssh-agent, but
that's not the point.

It would be interesting, to me at least, that git push --dry-run can do
its job through the git:// url instead of the ssh:// one. But for now,
all that does is telling me:
fatal: The remote end hung up unexpectedly
(probably because the git server doesn't allow pushes at all)

So, before I dive in, what would you think about such a feature?

There is one thing that bothers me, though, it's that --dry-run would,
in the end, not really be a dry-run anymore, and, for example, could
not be used to validate that the ssh setup is good without actually
pushing.

Cheers,

Mike