http-fetch: don't use double-slash as directory separator in URLs
Please see http://bugs.debian.org/409887
http-fetch expected the URL given at the command line to have a trailing
slash anyway, and then added '/objects...' when requesting objects files
from the http server.
Now it doesn't require the trailing slash in <url> anymore, and strips
trailing slashes if given nonetheless.
Signed-off-by: Gerrit Pape <pape@smarden.org> Signed-off-by: Junio C Hamano <junkio@cox.net>