revset: add support for using ~ operator on wdir() predicate We catch the WdirUnsupported exception and handles the wdir() case here.

revset: add support for p2(wdir()) to get second parent of working directory This adds support for finding the second parent of working directory using the p2 predicate.

revset: use try-except instead of if-else because of perf For wdir(), we now raises an exception which will be raised when wdir() will be passed, so catching that exception is better checking for wdir() using if-else.

revset: remove redundant condition and change to else from elif Before going to this piece of code, we already check whether n is in [0, 1, 2], so dropping the redundant condition.

tests: add tests for predicates and operators which works with wdir() This one is cluttering up the test file though.

revset: add support for "wdir()^n" This patch catches the WdirUnsupported exception raised, and adds support for wdir^n which will give us the nth parent of the working directory.

revset: add parentheses after wdir since its a function wdir was shown in help rather than wdir().

cmdutil: avoid redefining write() function in export if possible Doing less work inside the loop just feels better to me.

cmdutil: extract closure that performs the actual export formatting This simplifies things a little by making the actual act of turning a revision into patch data a single function. After this, adding formatter support to `hg export` should be much simpler.

cmdutil: use a generator expression instead of a list comprehension

cmdutil: rename template param to export to fntemplate It's actually a template for the filename, not a formatter template.

cmdutil: comprehensively document the interface of export I want to make some improvements here, but in order to make future patches easier to review I want to document the current state of the world.

tests: hide warning from test-xdg.t The test-xdg.t test uses the system hgrc because it unsets HGRCPATH. If the system has an extension enabled that doesn't work with the development version of Mercurial it prints an 'extension failed to load' warning. Let's just hide that by piping stderr to /dev/null.

policy: define C module versions individually This allows us to bump the version for a single module without changing all of them.