Why doesn't git-fetch obey -c "remote.origin.url" on the command-line?

On a git built from the master branch just now:

 $ ./git config remote.origin.url
https://code.google.com/p/git-core/
$ ./git -c remote.origin.url=git://git.sourceforge.jp/gitroot/git-core/git.git
config remote.origin.url
git://git.sourceforge.jp/gitroot/git-core/git.git
$ GIT_TRACE=1 ./git -c
remote.origin.url=git://git.sourceforge.jp/gitroot/git-core/git.git
fetch 2>&1 | head -n 2
trace: built-in: git 'fetch'
trace: run_command: 'git-remote-https' 'origin'
'https://code.google.com/p/git-core/'

I'd expect this to try to fetch from the remote.origin.url I specified on the command-line, but for some reason fetch doesn't pick that up. Isn't this a bug?

The use case for this is to have a script in cron that does a pull of repositories via http while the developers expecting to occasionally use those repositories as work directories should transparently be able to pull/push from them.

I know about remote.origin.pushurl, but I'd prefer pulls to also be over ssh in those cases, because then you don't have to worry about proxy settings (different for the devs & that automated script).

I could fix this, but I thought I'd first send a question about whether this shouldn't be considered a bug, and I haven't dug into this yet but I think that configuration passed via the -c option should *always* override any other config Git may get from elsewhere.