url: remove unnecessary deletion of environ variables while dealing with proxy Currently we delete proxy environment variables if ui.config contains proxy values. This is unnecessary because urllib2.ProxyHandler class only reads proxy from environment it is initialised by None. But url.py never passes None, so there is no point urllib2 will take environment variables in account. This also prevents deleting environment variables which is not safe. This code was introduced while resolving Bug 2451 even it is in one of comments (sixth one) on bug that we can safely remove this part. Link to bug : https://bz.mercurial-scm.org/show_bug.cgi?id=2451