mdiff: use str.startswith/endswith() instead of slicing

patch: unify check_binary and binary flags Follows up 079b27b5a869. If opts.text=True, check_binary is ignored, so we can just pass the binary flag to unidiff(). perfunidiff now takes any inputs as text files, which I think is a desired behavior.

py3: make sure we open the file in bytes mode # skip-blame because we are just adding b Differential Revision: https://phab.mercurial-scm.org/D2077

py3: use bytes instead of str Differential Revision: https://phab.mercurial-scm.org/D2076

py3: add b'' prefixes to string literals in test files # skip-blame because we are just adding b'' Differential Revision: https://phab.mercurial-scm.org/D2075

py3: use range instead of xrange xrange is not available on Python 3. Differential Revision: https://phab.mercurial-scm.org/D2074

py3: use open() instead of file() file() is not present in Python 3. Differential Revision: https://phab.mercurial-scm.org/D2073

py3: use pycompat.bytestr to convert _b85chars to bytes The tranformer does append b'' to the value and make that a bytes but bytes in Python 3 returns the ascii value on getting characters using indexing. Characters of this string are queried using indexing multiple times in the file and to support that we use pycompat.bytestr which returns the bytechrs using indexing. Differential Revision: https://phab.mercurial-scm.org/D2072

py3: use pycompat.bytechr instead of chr Differential Revision: https://phab.mercurial-scm.org/D2071

py3: use pycompat.ziplist instead of zip zip returns a zip object instead of a list on Python 3. Differential Revision: https://phab.mercurial-scm.org/D2070

patches: move assignment outside the conditional Having this movement in its own patch will make the next patch clearer.

sshpeer: remove support for connecting to <0.9.1 servers (BC) 197d10e157ce made this change for the HTTP peer. Let's do the same for the SSH peer. Test output changes as expected. A redundant test has been dropped. .. bc:: Support for connecting to Mercurial servers older than 0.9.1 has been removed. Differential Revision: https://phab.mercurial-scm.org/D2036

sshpeer: document the handshake mechanism The mechanism by which SSH peers establish connections with remotes is wonky and requires a bit of code archeology to understand. While it is already documented in `hg help internals.wireproto`, it helps to have documentation in the code as well. Differential Revision: https://phab.mercurial-scm.org/D2035

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