http-push: Make WebDAV work with (broken?) default apache2 WebDAV module

WebDAV on Debian unstable cannot handle renames on WebDAV from
file.ext to newfile (without ext) when newfile* already
exists. Normally, git creates a file like 'objects/xx/sha1.token',
which is renamed to 'objects/xx/sha1' when transferred completely.

Just use '_' instead of '.' so WebDAV doesn't see it as an extension
change.
Signed-off-by: NRutger Nijlunsing <git@tux.tmfweb.nl>
Acked-by: NJohannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: NJunio C Hamano <junkio@cox.net>

http-push.c

@@ -530,7 +530,7 @@ static void start_put(struct transfer_request *request)
 	request->dest = xmalloc(strlen(request->url) + 14);
 	sprintf(request->dest, "Destination: %s", request->url);
 	posn += 38;
-	*(posn++) = '.';
+	*(posn++) = '_';
 	strcpy(posn, request->lock->token);
 
 	slot = get_active_slot();