ui: add ignore-single-command functionality This closes the last feature gap other than the attend list from the extension. For now, I'm leaving the attend list in the extension, because I'm unsure it has merit in a world where commands have been updated to take advantage of the modern API.

ui: introduce neverpager() call I'm about to add direct paging support to some commands, and as a result we need a way to communicate from the higher layers of dispatch that paging is explicitly disabled.

pager: move more behavior into core This moves the global flag and the --pager=yes logic into core. Only functionality change is that users now always get a --pager flag and can enable the pager via the flag without the extension active. Moving the flag into core exposes a defect in the ro localization, which will have to be corrected later.

pager: move pager-initiating code into core No functionality change. A previous version of this API had a category argument on ui.pager(). As I migrated the commands in core, I couldn't come up with good enough consistency in any categorization scheme so I just scrapped the whole idea. It may be worth revisiting in the future.

test-logtoprocess: use cat to wait for outputs Commands started by logtoprocess are running asynchronously. To be able to test the output, we need to block and wait for the output. The patch uses "| cat" to wait for such "asynchronous" outputs, to make the test more reliable. I have also written a short notice at the top, hopefully people would be aware of the pitfall when changing the test.

chgserver: move comments in config example "#" must be the first character of a line to mark the text as comments. So let's change the docstring.

localrepo: move extension loading to a separate method The stateful chg plan [1] requires a special repo object, where ideally all side effects caused by loading the repo object could be reverted by just dropping (gabbage collect) the loaded repo object. Currently, that is impossible because repo.__init__ calls "extensions.loadall", which may have unpredictable side-effects that cannot be reverted by dropping the repo object. This patch moves "extensions.loadall" to a separate method, so chg could subclass localrepository and make extensions loading a no-op. [1]: mercurial-scm.org/pipermail/mercurial-devel/2017-February/092547.html

py3: convert the mode argument of os.fdopen to unicodes Couple of these from the earlier series got lost while rebasing. So this patch converts them again.

runtests: unindent an "if True" block The block was left to make review easier. This patch unindents it.

runtests: set web.ipv6 if we use IPv6 As explained by the previous patch, we need to set "web.ipv6=True" if we decide to use IPv6. Otherwise "hg serve" will still try to listen on IPv4. This patch makes it so by appending web.ipv6 to "extra configs". This patch was tested in a Linux system with IPv6, by the following steps: 1. Change hgweb/server.py temporarily to write a file if IPv6HTTPServer.__init__ is called. 2. run-tests.py -l --keep-tmpdir test-serve.t 3. Check the generated .hgrc, make sure it sets web.ipv6=1. 4. Check the log file to make sure IPv6HTTPServer.__init__ is called.