transaction: tests we don't overwrite branch changes on abort

We actually do not! Great.

…Why are doing a backup of the `branch` files at transaction creation then‽

tests/test-transaction-wc-rollback-race.t

@@ -1,157 +1,190
 =======================================================================
 Check potential race condition around transaction and working copy data
 =======================================================================
 
 #testcases bookmarks-in-store bookmarks-wc-level
 
 The transaction is garanteed to run with the lock, but may runs without the
 wlock. So if the transaction backup/restore some content related to the
 working-copy and protected by the wlock, we might run into trouble if another
 process grab the wlock and modify them.
 
 This test file is testing various cases where such parallel changes happens to
 validate the transaction behavior.
 
 Other is used to get a simple pull source. As pull is a simple way to create
 transaction without the wlock.
 
 Setup
 =====
 
 Avoid long deadlock
 
   $ cat << EOF >> $HGRCPATH
   > [ui]
   > timeout=10
   > EOF
 
 #if bookmarks-in-store
   $ cat << EOF >> $HGRCPATH
   > [format]
   > bookmarks-in-store = yes
   > EOF
 #endif
 
 
   $ hg init repo
   $ cd repo
   $ for filename in a b c d e f g h i j k l m; do
   >     echo $filename > default_$filename
   >     hg add default_$filename
   >     hg commit --quiet --message default_$filename
   > done
   $ hg bookmark --rev . foo
   $ hg branch babar
   marked working directory as branch babar
   (branches are permanent and global, did you want a bookmark?)
   $ for filename in a b c d e f g h i j k l m; do
   >     echo $filename > babar_$filename
   >     hg add babar_$filename
   >     hg commit --quiet --message babar_$filename
   > done
   $ hg bookmark --rev . bar
   $ hg up 'desc("default_m")'
   0 files updated, 0 files merged, 13 files removed, 0 files unresolved
   $ hg log -G -T '[{branch}] ({bookmarks}) {desc}\n'
   o  [babar] (bar) babar_m
   |
   o  [babar] () babar_l
   |
   o  [babar] () babar_k
   |
   o  [babar] () babar_j
   |
   o  [babar] () babar_i
   |
   o  [babar] () babar_h
   |
   o  [babar] () babar_g
   |
   o  [babar] () babar_f
   |
   o  [babar] () babar_e
   |
   o  [babar] () babar_d
   |
   o  [babar] () babar_c
   |
   o  [babar] () babar_b
   |
   o  [babar] () babar_a
   |
   @  [default] (foo) default_m
   |
   o  [default] () default_l
   |
   o  [default] () default_k
   |
   o  [default] () default_j
   |
   o  [default] () default_i
   |
   o  [default] () default_h
   |
   o  [default] () default_g
   |
   o  [default] () default_f
   |
   o  [default] () default_e
   |
   o  [default] () default_d
   |
   o  [default] () default_c
   |
   o  [default] () default_b
   |
   o  [default] () default_a
   
 
   $ cat << EOF >> ../txn-close.sh
   > rm -f $TESTTMP/transaction-continue
   > $RUNTESTDIR/testlib/wait-on-file 5 $TESTTMP/transaction-continue $TESTTMP/transaction-waiting
   > rm -f $TESTTMP/transaction-waiting
   > exit 1
   > EOF
   $ cat << EOF >> .hg/hgrc
   > [hooks]
   > pretxnclose.test = sh $TESTTMP/txn-close.sh
   > EOF
 
 Check the overall logic is working, the transaction is holding the `lock` , but
 not the `wlock`, then get aborted on a signal-file.
 
   $ hg phase --rev 0
   0: draft
   $ hg phase --public --rev 0 2> ../log.err &
   $ $RUNTESTDIR/testlib/wait-on-file 5 $TESTTMP/transaction-waiting
   $ echo y | hg --config ui.interactive=yes debuglock --set-wlock
   ready to release the lock (y)?  y
   $ echo y | hg --config ui.interactive=yes debuglock --set-lock
   abort: lock is already held
   [255]
   $ touch $TESTTMP/transaction-continue
   $ wait
   $ hg phase --rev 0
   0: draft
   $ cat ../log.err
   transaction abort!
   rollback completed
   abort: pretxnclose.test hook exited with status 1
 
 Actual testing
 ==============
 
 Changing tracked file
 ---------------------
 
   $ hg status
   $ hg phase --public --rev 0 2> ../log.err &
   $ $RUNTESTDIR/testlib/wait-on-file 5 $TESTTMP/transaction-waiting
   $ hg forget default_a
   $ hg status
   R default_a
   $ touch $TESTTMP/transaction-continue
   $ wait
   $ hg status
   R default_a (missing-correct-output !)
   $ hg revert --all --quiet
+
+Changing branch from default
+----------------------------
+
+  $ hg branch
+  default
+  $ hg phase --public --rev 0 2> ../log.err &
+  $ $RUNTESTDIR/testlib/wait-on-file 5 $TESTTMP/transaction-waiting
+  $ hg branch celeste
+  marked working directory as branch celeste
+  $ hg branch
+  celeste
+  $ touch $TESTTMP/transaction-continue
+  $ wait
+  $ hg branch
+  celeste
+
+Changing branch from another one
+--------------------------------
+
+  $ hg up babar --quiet
+  $ hg branch
+  babar
+  $ hg phase --public --rev 0 2> ../log.err &
+  $ $RUNTESTDIR/testlib/wait-on-file 5 $TESTTMP/transaction-waiting
+  $ hg branch celeste
+  marked working directory as branch celeste
+  $ hg branch
+  celeste
+  $ touch $TESTTMP/transaction-continue
+  $ wait
+  $ hg branch
+  celeste