tests/test-convert-bzr-114.t

commandserver: add new forking server implemented without using SocketServer

SocketServer.ForkingMixIn of Python 2.x has a couple of issues, such as:

 - race condition that leads to 100% CPU usage (Python 2.6)
   https://bugs.python.org/issue21491
 - can't wait for children belonging to different process groups (Python 2.6)
 - leaves at least one zombie process (Python 2.6, 2.7)
   https://bugs.python.org/issue11109

The first two are critical because we do setpgid(0, 0) in child process to
isolate terminal signals. The last one isn't, but ForkingMixIn seems to be
doing silly. So there are two choices:

 a) backport and maintain SocketServer until we can drop support for Python 2.x
 b) replace SocketServer by simpler one and eliminate glue codes

I chose (b) because it's great time for getting rid of utterly complicated
SocketServer stuff, and preparing for future move towards prefork service.

New unixforkingservice is implemented loosely based on chg 531f8ef64be6. It
is monolithic but much simpler than SocketServer. unixservicehandler provides
customizing points for chg, and it will be shared with future prefork service.

Old unixservice class is still used by chgserver. It will be removed later.

Thanks to Jun Wu for investigating these issues.

#require bzr bzr114

  $ . "$TESTDIR/bzr-definitions"

The file/directory replacement can only be reproduced on
bzr >= 1.4. Merge it back in test-convert-bzr-directories once
this version becomes mainstream.
replace file with dir

  $ mkdir test-replace-file-with-dir
  $ cd test-replace-file-with-dir
  $ bzr init -q source
  $ cd source
  $ echo d > d
  $ bzr add -q d
  $ bzr commit -q -m 'add d file'
  $ rm d
  $ mkdir d
  $ bzr add -q d
  $ bzr commit -q -m 'replace with d dir'
  $ echo a > d/a
  $ bzr add -q d/a
  $ bzr commit -q -m 'add d/a'
  $ cd ..
  $ hg convert source source-hg
  initializing destination source-hg repository
  scanning source...
  sorting...
  converting...
  2 add d file
  1 replace with d dir
  0 add d/a
  $ manifest source-hg tip
  % manifest of tip
  644   d/a
  $ cd source-hg
  $ hg update
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd ../..