sshpeer: move handshake outside of sshpeer With the handshake now performed before a peer class is instantiated, we can now instantiate a different peer class depending on the results of the handshake. Our test extension had to change to cope with the new API. Because we now issue the command via raw I/O calls and don't call _callstream(), we no longer have to register the fake command. (_callstream() uses the command registration to see what args to send). Differential Revision: https://phab.mercurial-scm.org/D2034

sshpeer: inline I/O into _validaterepo() We want to move the handshake code out of the peer class so the peer factory function can perform the handshake and instantiate a proper class depending on the results. To make that refactor easier to read, we first inline I/O functionality into _validaterepo(). Test output for low-level protocol tests didn't change, thus hopefully demonstrating that this refactor didn't change any material behavior. Because we no longer call _callstream(), our test extension for monkeypatching the peer had to change its hook point. Differential Revision: https://phab.mercurial-scm.org/D2033

sshpeer: clean up API for sshpeer.__init__ (API) Our refactoring left the state of sshpeer.__init__ in a poor state. "create" was no longer used. Process/pipe arguments were passed poorly. "name" was really a URL. This commit cleans all that up. .. api:: sshpeer.sshpeer.__init__ now receives arguments describing an existing connection instead of creating a connection itself. Differential Revision: https://phab.mercurial-scm.org/D2032

sshpeer: establish SSH connection before class instantiation We want to move the handshake to before peers are created so we can instantiate a different peer class depending on the results of the handshake. This necessitates moving the SSH process invocation to outside the peer class. As part of the code move, some variables were renamed for clarity. util.popen4() returns stdin, stdout, and stderr in their typical file descriptor order. However, stdin and stdout were being mapped to "pipeo" and "pipei" respectively. "o" for "stdin" and "i" for "stdout" is a bit confusing. Although it does make sense for "output" and "input" from the perspective of the client. But in the context of the new function, it makes sense to refer to these as their file descriptor names. In addition, the last use of self._path disappeared, so we stop setting that attribute and we can delete the redundant URL parsing necessary to set it. Differential Revision: https://phab.mercurial-scm.org/D2031