tests/test-logexchange.t

atomicupdate: add an experimental option to use atomictemp when updating

In some cases Mercurial truncating files when updating causes problems. It can
happens when processes are currently reading the file or with big file or on
NFS mounts.

We add an experimental option to use the atomictemp option of vfs.__call__ in
order to avoid the problem.

The localrepository.wwrite seems to assume the files are created without the
`x` flag; with atomictempfile, the new file might inherit the `x` flag from
the destination. We force remove it afterward. This code could be refactored
and the flag processing could be moved inside vfs.

This patch should be tested with
`--extra-config-opt experimental.update.atomic-file=True`
as we disabled the option by default.

Differential Revision: https://phab.mercurial-scm.org/D1882

Testing the functionality to pull remotenames
=============================================

  $ cat >> $HGRCPATH << EOF
  > [alias]
  > glog = log -G -T '{rev}:{node|short}  {desc}'
  > [experimental]
  > remotenames = True
  > EOF

Making a server repo
--------------------

  $ hg init server
  $ cd server
  $ for ch in a b c d e f g h; do
  >   echo "foo" >> $ch
  >   hg ci -Aqm "Added "$ch
  > done
  $ hg glog
  @  7:ec2426147f0e  Added h
  |
  o  6:87d6d6676308  Added g
  |
  o  5:825660c69f0c  Added f
  |
  o  4:aa98ab95a928  Added e
  |
  o  3:62615734edd5  Added d
  |
  o  2:28ad74487de9  Added c
  |
  o  1:29becc82797a  Added b
  |
  o  0:18d04c59bb5d  Added a
  
  $ hg bookmark -r 3 foo
  $ hg bookmark -r 6 bar
  $ hg up 4
  0 files updated, 0 files merged, 3 files removed, 0 files unresolved
  $ hg branch wat
  marked working directory as branch wat
  (branches are permanent and global, did you want a bookmark?)
  $ echo foo >> bar
  $ hg ci -Aqm "added bar"

Making a client repo
--------------------

  $ cd ..

  $ hg clone server client
  updating to branch default
  8 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ cd client
  $ cat .hg/logexchange/bookmarks
  0
  
  87d6d66763085b629e6d7ed56778c79827273022\x00file:$TESTTMP/server\x00bar (esc)
  62615734edd52f06b6fb9c2beb429e4fe30d57b8\x00file:$TESTTMP/server\x00foo (esc)

  $ cat .hg/logexchange/branches
  0
  
  ec2426147f0e39dbc9cef599b066be6035ce691d\x00file:$TESTTMP/server\x00default (esc)
  3e1487808078543b0af6d10dadf5d46943578db0\x00file:$TESTTMP/server\x00wat (esc)

Making a new server
-------------------

  $ cd ..
  $ hg init server2
  $ cd server2
  $ hg pull ../server/
  pulling from ../server/
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 9 changesets with 9 changes to 9 files (+1 heads)
  adding remote bookmark bar
  adding remote bookmark foo
  new changesets 18d04c59bb5d:3e1487808078
  (run 'hg heads' to see heads)

Pulling form the new server
---------------------------
  $ cd ../client/
  $ hg pull ../server2/
  pulling from ../server2/
  searching for changes
  no changes found
  $ cat .hg/logexchange/bookmarks
  0
  
  62615734edd52f06b6fb9c2beb429e4fe30d57b8\x00file:$TESTTMP/server\x00foo (esc)
  87d6d66763085b629e6d7ed56778c79827273022\x00file:$TESTTMP/server\x00bar (esc)
  87d6d66763085b629e6d7ed56778c79827273022\x00file:$TESTTMP/server2\x00bar (esc)
  62615734edd52f06b6fb9c2beb429e4fe30d57b8\x00file:$TESTTMP/server2\x00foo (esc)

  $ cat .hg/logexchange/branches
  0
  
  3e1487808078543b0af6d10dadf5d46943578db0\x00file:$TESTTMP/server\x00wat (esc)
  ec2426147f0e39dbc9cef599b066be6035ce691d\x00file:$TESTTMP/server\x00default (esc)
  ec2426147f0e39dbc9cef599b066be6035ce691d\x00file:$TESTTMP/server2\x00default (esc)
  3e1487808078543b0af6d10dadf5d46943578db0\x00file:$TESTTMP/server2\x00wat (esc)