push: anonymize URLs in error messages and warnings

push: anonymize URLs in error messages and warnings

Just like 47abd85ba0 (fetch: Strip usernames from url's before storing
them, 2009-04-17) and later 882d49ca5c (push: anonymize URL in status
output, 2016-07-13), and even later c1284b21f243 (curl: anonymize URLs
in error messages and warnings, 2019-03-04) this change anonymizes URLs
(read: strips them of user names and especially passwords) in
user-facing error messages and warnings.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Reviewed-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>