sshpeer: move URL validation out of sshpeer.__init__ We will soon have another SSH peer class to support the new version of the SSH protocol. However, we won't know which peer class to instantiate until we perform a handshake on an active connection. This means that we need to move connection establishment and handshake code out of sshpeer.__init__. This commit starts the process of migrating peer creation code out of sshpeer.__init__ into instance(), which is the API for creating peers. The moved code no longer calls _abort(). _abort() runs _cleanup() and raises. _cleanup() only performs actions on self._pipe*. These objects aren't instantiated until we actually connect to the peer. So _abort() was not necessary in the old code. To keep the API the same, __init__() now makes a redundant call to util.url(). This will be fixed in subsequent commits. Differential Revision: https://phab.mercurial-scm.org/D2027