httppeer: reintroduce _abort that accidentally was removed in 167047ba3cfa

Including the missing test coverage that would have caught it.
hgweb: replace excanvas.js with a newer version

The current version of excanvas is unknown.  Substitute it with the
latest version from the excanvas website:

http://code.google.com/p/explorercanvas/

Instead of using the "compiled" version, just use the readable one.
color: add missing handling of stderr capture introduced by 350dc24a553d

It wouldn't raise exception without this change, but _bufferstates was wrong
because of missing _bufferstates.pop() in colorui.popbuffer().
match: fix NameError 'pat' on overflow of regex pattern length

'pat' was renamed to 'regex' in 9d28fd795215.
exchange: fix invalid reference to bundle2.UnknownPartError caught by pyflakes
win32: add missing definition of _ERROR_NO_MORE_FILES caught by pyflakes
killdaemons: correct typo of _check() function caught by pyflakes
cmdserver: forcibly use L channel to read password input (issue3161)

Command server is designed to use the channel protocol even if the server
process is accessible to tty, whereas vanilla hg should be able to read
password from tty in that case.  So it isn't enough to swap sys.stdin:

    # works only if the server process is detached from the console
    sys.stdin = self.fin
    getpass.getpass('')
    sys.stdin = oldin

or test isatty:

    # vanilla hg can't talk to tty if stdin is redirected
    if self._isatty(self.fin):
        return getpass.getpass('')
    else:
        ...

Since ui.nontty flag is undocumented and command-server channels don't provide
isatty(), this change won't affect the other uses of ui._isatty().

issue3161 also suggests to provide some context of messages.  I think it can
be implemented by using the generic templating function.
largefiles: remove directories emptied after their files are moved (issue3515)
rebase: don't abort if we're asked to rebase an empty revset

The documentation says we exit 1 if we have nothing to do, so avoid
breaking that contract when we're passed an empty revset.

This was changed in http://www.selenic.com/hg/rev/a259f7b488ab to
improve the error message; keep the improved message, just not the
abort.
discovery: don't report all "unsynced" remote heads (issue4230)

8a9e0b523d2d made discovery more helpful - too helpful for some extreme use
cases.

Instead, we arbitrarily limit the list it at 4 and add 'or more'.
graft: do not use `.remove` on a smart set (regression)

Revset calls use to return a list. Graft use to mutate that list. We cannot do
this anymore leading to a crash when grafting multiple changeset with a revset.

    File ".../mercurial/commands.py", line 3117, in graft
      revs.remove(rev)
    AttributeError: '_addset' object has no attribute 'remove'

We are late in code-freeze so we make the shortest possible fix by turning it
back to a list.
revset: fix revision filtering in spanset.contains (regression)

The argument is `x` but the variable tested for filtering is `rev`. `rev`
happens to be a revset methods, ... never part of the filtered revs. This
method is now using `rev` for everything.
revsetbenchmark: fix error raising

We want to display the commands, not all arguments of the function. (The old
code actually crash, failing to joining a list of lists.)
ancestor: silence multiple ancestor warning outside of merge (issue4234)

The current situation is a bit of a layering violation as
merge-specific knowledge is pushed down to lower layers and leaks
merge assumptions into other code paths.

Here, we simply silence the warning with a hack. Both the warning and
the hack will probably go away in the near future when bid merge is
made the default.
revset: inline spanset containment check (fix perf regression)

Calling a function is super expensive in python. We inline the trivial range
comparison to get back to more sensible performance on common revset operation.

Benchmark result below:

Revision mapping:
0) 3f83fc5cfe71 2.9.2 release
1) bcfd44abad93 current @
2) This revision


revset #0: public()
0) wall 0.010890 comb 0.010000 user 0.010000 sys 0.000000 (best of 201)
1) wall 0.012109 comb 0.010000 user 0.010000 sys 0.000000 (best of 199)
2) wall 0.012211 comb 0.020000 user 0.020000 sys 0.000000 (best of 197)

revset #1: :10000 and public()
0) wall 0.007141 comb 0.010000 user 0.010000 sys 0.000000 (best of 361)
1) wall 0.014139 comb 0.010000 user 0.010000 sys 0.000000 (best of 186)
2) wall 0.008334 comb 0.010000 user 0.010000 sys 0.000000 (best of 308)

revset #2: draft()
0) wall 0.009610 comb 0.010000 user 0.010000 sys 0.000000 (best of 279)
1) wall 0.010942 comb 0.010000 user 0.010000 sys 0.000000 (best of 243)
2) wall 0.011036 comb 0.010000 user 0.010000 sys 0.000000 (best of 239)

revset #3: :10000 and draft()
0) wall 0.006852 comb 0.010000 user 0.010000 sys 0.000000 (best of 383)
1) wall 0.014641 comb 0.010000 user 0.010000 sys 0.000000 (best of 183)
2) wall 0.008314 comb 0.010000 user 0.010000 sys 0.000000 (best of 299)

We can see this changeset gains back the regression for `and` operation on
spanset.  We are still a bit slowerfor the `public()` and `draft()`. Predicates
not touched by this changeset.
revset: also inline spanset._contained in __len__

For consistency with what happen in `__contains__`, we inline the range test
into `__len__` too.
transaction: fix file descriptor leak for journal.backupfiles

The journal.backupfiles descriptor wasn't being closed. This resulted in
hgsubversion test runs having a bagillion descriptors open, which crashed on
platforms with low open file limits (like OSX).
spanset: directly use __contains__ instead of a lambda

Spanset are massively used in revset. First because the initial subset itself is
a repo wide spanset. We speed up the __and__ operation by getting rid of a
gratuitous lambda call. A more long terms solution would be to:

1. speed up operation between spansets,
2. have a special smartset for `all` revisions.

In the mean time, this is a very simple fix that buyback some of the performance
regression.

Below is performance benchmark for trival `and` operation between two spansets.
(Run on an unspecified fairly large repository.)

revset tip:0
2.9.2)  wall 0.282543 comb 0.280000 user 0.260000 sys 0.020000 (best of 35)
before) wall 0.819181 comb 0.820000 user 0.820000 sys 0.000000 (best of 12)
after)  wall 0.645358 comb 0.650000 user 0.650000 sys 0.000000 (best of 16)

Proof of concept implementation of an `all` smartset brings this to 0.10 but it's
too invasive for stable.
help: clarify distinction among `contains`/`file`/`filelog`

For a Mercurial new-comer, the distinction between `contains(x)`,
`file(x)`, and `filelog(x)` in the "revsets" help page may not be
obvious. This commit tries to make things more obvious (text based on
an explanation from Matt in an FB group thread).