ui: add special-purpose atexit functionality
In spite of its longstanding use, Python's built-in atexit code is
not suitable for Mercurial's purposes, for several reasons:
* Handlers run after application code has finished.
* Because of this, the code that runs handlers swallows exceptions
(since there's no possible stacktrace to associate errors with).
If we're lucky, we'll get something spat out to stderr (if stderr
still works), which of course isn't any use in a big deployment
where it's important that exceptions get logged and aggregated.
* Mercurial's current atexit handlers make unfortunate assumptions
about process state (specifically stdio) that, coupled with the
above problems, make it impossible to deal with certain categories
of error (try "hg status > /dev/full" on a Linux box).
* In Python 3, the atexit implementation is completely hidden, so
we can't hijack the platform's atexit code to run handlers at a
time of our choosing.
As a result, here's a perfectly cromulent atexit-like implementation
over which we have control. This lets us decide exactly when the
handlers run (after each request has completed), and control what
the process state is when that occurs (and afterwards).
Issue586: removing remote files after merge appears to corrupt the
dirstate
$ hg init a
$ cd a
$ echo a > a
$ hg ci -Ama
adding a
$ hg init ../b
$ cd ../b
$ echo b > b
$ hg ci -Amb
adding b
$ hg pull -f ../a
pulling from ../a
searching for changes
warning: repository is unrelated
requesting all changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files (+1 heads)
(run 'hg heads' to see heads, 'hg merge' to merge)
$ hg merge
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ hg rm -f a
$ hg ci -Amc
$ hg st -A
C b
$ cd ..
Issue1433: Traceback after two unrelated pull, two move, a merge and
a commit (related to issue586)
create test repos
$ hg init repoa
$ touch repoa/a
$ hg -R repoa ci -Am adda
adding a
$ hg init repob
$ touch repob/b
$ hg -R repob ci -Am addb
adding b
$ hg init repoc
$ cd repoc
$ hg pull ../repoa
pulling from ../repoa
requesting all changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files
(run 'hg update' to get a working copy)
$ hg update
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ mkdir tst
$ hg mv * tst
$ hg ci -m "import a in tst"
$ hg pull -f ../repob
pulling from ../repob
searching for changes
warning: repository is unrelated
requesting all changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files (+1 heads)
(run 'hg heads' to see heads, 'hg merge' to merge)
merge both repos
$ hg merge
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ mkdir src
move b content
$ hg mv b src
$ hg ci -m "import b in src"
$ hg manifest
src/b
tst/a
$ cd ..