hghave: change ssl check to just check ssl module Previously, the "ssl" check effectively looked for PyOpenSSL or Python 2.7.9. After this patch, we simply look for just the "ssl" module. After d962e955da08, there have been no references to PyOpenSSL in the tree (the previous usage of PyOpenSSL was to implement ssl support on old, no longer supported Python versions that didn't have an ssl module (e.g. Python 2.4). So, the check for PyOpenSSL served no purpose. Pythons we support ship with the ssl module. Although it may not be available in all installations. So, we still need the check for whether the ssl module imports, hence the hghave check. The main side-effect of this change is that we now run test-https.t (the only test requiring the "ssl" hghave feature) on Python <2.7.9 when PyOpenSSL is not installed (which is probably most installations) and the ssl module is available. Before, we wouldn't run this test on these older Python versions. I confirmed that test-https.t passes with Python 2.6.9 and 2.7.8 on OS X 10.11.

help: document sharing of revlog header with revision 0 The previous docs were incorrect about there being a discrete header on revlogs.

mpatch: move collect() to module level This helps the code read a little more clearly.

mpatch: un-nest the move() method This helps the code read a little more clearly.

mpatch: move pull() method to top level There was no need for this to be nested.

chgserver: use old ui.system if fout is not stdout or needs to be captured Before this patch, chgui will override the system method, forwarding every process execution to the client so sessions and process groups can work as expected. But the chg client will just use stdout, if ui.fout is not stdout or if the output is set to be captured to safe._buffers, the client will not behave correctly. This can happen especially with code prepending "remote:". For example, bundle2 uses ui.pushbuffer, and sshpeer sets fout to ferr. We may have trouble with interactive commands in the fout set to ferr case but if it really bites us, we can always send file descriptors to the client. This patch adds a check to detect the above situations and fallback to the old ui.system if so. It will make chg happy with test-bundle2-exchange.t, test-phases-exchange.t, test-ssh-bundle1.t and test-ssh.t.

node: use byte literals to construct nullid and wdirid Python 3's hex() insists on operating on bytes. This patch gives it what it wants. '' and b'' in Python 2 are equivalent, so this has no impact on Python 2.

tests: try to import modules with Python 3 All of mercurial.* is now using absolute_import. Most of mercurial.* is able to ast parse with Python 3. The next big hurdle is being able to import modules using Python 3. This patch adds testing of hgext.* and mercurial.* module imports in Python 3. As the new test output shows, most modules can't import under Python 3. However, many of the failures are due to a common problem in a highly imported module (e.g. the bytes vs str issue in node.py).