tests/test-glog-topological.t

util: fix race in makedirs()

Update makedirs() to ignore EEXIST in case someone else has already created the
directory in question.  Previously the ensuredirs() function existed, and was
nearly identical to makedirs() except that it fixed this race.  Unfortunately
ensuredirs() was only used in 3 places, and most code uses the racy makedirs()
function.  This fixes makedirs() to be non-racy, and replaces calls to
ensuredirs() with makedirs().

In particular, mercurial.scmutil.origpath() used the racy makedirs() code,
which could cause failures during "hg update" as it tried to create backup
directories.

This does slightly change the behavior of call sites using ensuredirs():
previously ensuredirs() would throw EEXIST if the path existed but was a
regular file instead of a directory.  It did this by explicitly checking
os.path.isdir() after getting EEXIST.  The makedirs() code did not do this and
swallowed all EEXIST errors.  I kept the makedirs() behavior, since it seemed
preferable to avoid the extra stat call in the common case where this directory
already exists.  If the path does happen to be a file, the caller will almost
certainly fail with an ENOTDIR error shortly afterwards anyway.  I checked
the 3 existing call sites of ensuredirs(), and this seems to be the case for
them.

This test file aims at test topological iteration and the various configuration it can has.

  $ cat >> $HGRCPATH << EOF
  > [ui]
  > logtemplate={rev}\n
  > EOF

On this simple example, all topological branch are displayed in turn until we
can finally display 0. this implies skipping from 8 to 3 and coming back to 7
later.

  $ hg init test01
  $ cd test01
  $ hg unbundle $TESTDIR/bundles/remote.hg
  adding changesets
  adding manifests
  adding file changes
  added 9 changesets with 7 changes to 4 files (+1 heads)
  (run 'hg heads' to see heads, 'hg merge' to merge)

  $ hg log -G
  o  8
  |
  | o  7
  | |
  | o  6
  | |
  | o  5
  | |
  | o  4
  | |
  o |  3
  | |
  o |  2
  | |
  o |  1
  |/
  o  0
  

(display all nodes)

  $ hg --config experimental.graph-group-branches=1 log -G
  o  8
  |
  o  3
  |
  o  2
  |
  o  1
  |
  | o  7
  | |
  | o  6
  | |
  | o  5
  | |
  | o  4
  |/
  o  0
  

(revset skipping nodes)

  $ hg --config experimental.graph-group-branches=1 log -G --rev 'not (2+6)'
  o  8
  |
  o  3
  :
  o  1
  |
  | o  7
  | :
  | o  5
  | |
  | o  4
  |/
  o  0
  

(begin) from the other branch

  $ hg --config experimental.graph-group-branches=1 --config experimental.graph-group-branches.firstbranch=5 log -G
  o  7
  |
  o  6
  |
  o  5
  |
  o  4
  |
  | o  8
  | |
  | o  3
  | |
  | o  2
  | |
  | o  1
  |/
  o  0