formatting: enforce system headers before local headers Differential Revision: https://phab.mercurial-scm.org/D2275

wireprotoserver: add version to HTTP protocol name (API) This matches what we did for the SSH protocol handler in ac33dc94e1d5. .. api:: HTTP protocol handlers now advertises its internal name as ``http-v1`` instead of ``http``. Differential Revision: https://phab.mercurial-scm.org/D2219

wireprotoserver: rename webproto to httpv1protocolhandler This matches our naming convention for the SSH server's protocol handler. Differential Revision: https://phab.mercurial-scm.org/D2218

wireproto: improve docstring for "hello" Differential Revision: https://phab.mercurial-scm.org/D2217

httppeer: remove httpspeer All it did was verify at construction time that Mercurial supports TLS. instance() is what's used to construct peer instances. So we can just inline this check into that function and do away with the type variant. Differential Revision: https://phab.mercurial-scm.org/D2216

httppeer: remove redundant code to fetch capabilities _fetchcaps() is called by httppeer.instance(), which is the only instantiator of httppeer. Since _fetchcaps() always sets self._caps and since 197d10e157ce removed the fallback for cases where the remote doesn't support capabilities, we can remove some dead code from httppeer.capabilities(). Differential Revision: https://phab.mercurial-scm.org/D2215

httppeer: change logic around argument handling The code to process arguments only makes sense if there are arguments. So change an "else" to "elif args", remove an "if" that isn't necessary, and add some docs for good measure. Differential Revision: https://phab.mercurial-scm.org/D2214

tests: test using both versions of SSH protocol Now that the version 2 of the SSH protocol is usable in core, we can start actively testing it more widely outside of low-level protocol tests. We add #testcases variants to a handful of tests so we exercise both version 1 and version 2 of the SSH protocol when testing. This will allow us to more easily find regressions and variances as protocol 2 is developed. It will also make it easier to continue testing with protocol version 1 once version 2 is enabled by default. There are a handful of tests using ssh:// that should also gain test variances. One - test-push-race.t - already has a #testcases. This would require combinatorial cases. I didn't want to go down that rabbit hole, so that test is unchanged. Thinking aloud, there is probably an opportunity to automatically run tests with multiple server/protocol implementations. Ideally any test that performed server interaction would run with all supported server implementations and protocols so we could find variances between servers and protocols. But this has been a long-standing issue with our test harness. I don't think it is an easily solved problem. But it would be nice... Differential Revision: https://phab.mercurial-scm.org/D2206

sshpeer: log remote capabilities after protocol upgrade This helps reduce variance with version 1 and will help prevent test output divergence as we start testing protocol version 2 more widely. Differential Revision: https://phab.mercurial-scm.org/D2205

wireprotoserver: handle SSH protocol version 2 upgrade requests This commit teaches the SSH server to recognize the "upgrade" request line that clients send when they wish to switch the channel to version 2 of the SSH protocol. Servers don't honor upgrade requests unless an experimental config option is set. Since the built-in server now supports upgrade requests, our test server to test the handshake has been deleted. Existing tests use the built-in server and their output doesn't change. The upgrade is handled in our state machine. The end result is a bit wonky, as the server transitions back to version 1 state immediately after upgrading. But this will change as soon as version 2 has an actual protocol that differs from version 1. Tests demonstrating that the new server is a bit more strict about the upgrade handshake have been added. Differential Revision: https://phab.mercurial-scm.org/D2204