mercurial: man-in-the-middle attack

a security flaw was found in the way Mercurial handled subject Common Name field of the provided certificate (the check if the commonName in the received certificate matches the requested hostname was not performed). An attacker, able to get a carefully-crafted certificate signed by a Certificate Authority could use the certificate during a man-in-the-middle attack and potentially confuse Mercurial into accepting it by mistake.