templatekw: add 'requires' flag to switch to exception-safe interface The current templatekw interface, f(repo, ctx, templ, **args), is horrible because it's quite easy to encounter TypeError, ValueError, etc. It's also bad for Python 3 porting due to the **kwargs issue. This patch introduces a flag to switch to new f(context, mapping) API seen in templater functions. The requirement spec isn't verified (yet) because context.resource() can gracefully raise a ResourceUnavailable exception, but it's planned to be used as a filter in the help, such as "Revision Keywords" (if 'ctx' in requires), "File Keywords" (if 'fctx' in requires), etc. showauthor() is ported to the new API as an example. 20 more follows.

templater: specialize ResourceUnavailable error so that it can be caught See the next patch how it will be used.

templater: move specialized exception types to top I'm going to add one more exception type.

templatekw: minimize resource dependency of {envvars} and {termwidth} These keywords can be evaluated without a repo.

templatekw: simply override {graphwidth} function by mapping variable

remotenames: drop redundant templatekw names from help text Also removed the second "List of" phrase, which is obvious from the type "List of strings."

narrow: drop redundant templatekw/revset names from help text ":<name>:" is automatically added by the registrar.

run-tests: don't mask errors when a server fails to start There are sporadic instances of this on Windows. They seem to happen more frequently after the test machine is rebooted, although the only way to hit it on my laptop is to loop certain tests with -j9 for hours. The problem with masking out the specific failure is that there's no way to know if it's the same line in the test that's failing, or if it is random. The justification for adding this masking in 52e9e63f1495 was that the failures occur regularly, but that's not the case anymore. The port number is still printed, in case that turns out to be useful.

py3: use bytes instead of str in isinstance Internally we use bytes everywhere, and str on Python 3 is unicodes, so we need to make sure we are doing the right check. Differential Revision: https://phab.mercurial-scm.org/D2458

py3: convert a map expression into list comprehension map returns a map object on Python 3 and here we wanted a list instead. Differential Revision: https://phab.mercurial-scm.org/D2456

py3: use email.generator module instead of email.Generator On py2: >>> import email >>> import email.generator as emailgen >>> email.Generator.Generator is emailgen.Generator True email.Generator is not present on Python 3. Differential Revision: https://phab.mercurial-scm.org/D2454

py3: use pycompat.strkwargs to convert kwargs keys to str Differential Revision: https://phab.mercurial-scm.org/D2452

py3: whitelist test-push-http.t as passing Differential Revision: https://phab.mercurial-scm.org/D2451

util: handle fileno() on Python 3 throwing io.UnsupportedOperation Fortunately, the exception exists on Python 2 so we don't have to do something weirder than this. Differential Revision: https://phab.mercurial-scm.org/D2450