Environment to run tests in, changing file permissions on Cygwin

[Dr Rainer Woitok]

Greetings,

after recently updating my local clone  of the Mercurial source reposit-
ory to 3.7-rc+epsilon  I ran "make tests" just for the fun of it ... and
received plenty of output.  Among other things the output contained

--- /home/Rainer/repo/mercurial/tests/test-run-tests.t
+++ /home/Rainer/repo/mercurial/tests/test-run-tests.t.err
@@ -241,21 +241,21 @@
 ======================

   $ rt --debug 2>&1 | grep -v pwd
-  + echo *SALT* 0 0 (glob)
+  Trace: echo SALT1453980545 0 0
   *SALT* 0 0 (glob)
-  + echo babar
+  Trace: echo babar
   babar

which obviously originated in my shell running with environment variable
"PS4" being set to "Trace:".   After checking my other environment vari-
ables for additional suspects which might foul the Mercurial test suite,
I ran "make tests"  in a slightly reduced  environment with  much better
results:

$ unset CDPATH PS4
$ export HGPLAINEXCEPT= HGRCPATH= LANG=C LC_ALL=C
$ make tests

Perhaps "run-tests.py"  should be a bit more  restictive regarding vari-
ables inherited from the environment.   Should it inherit more than just
"PATH"?

Still the output produced by "run-tests.py" differs from what is expect-
ed.  Many,  but as far as I can see  not all deviations  have to do with
changes to a  file's permissions,  which are not recognized  by my local
Mercurial clone, as in:

--- /home/Rainer/repo/mercurial/tests/test-revert.t
+++ /home/Rainer/repo/mercurial/tests/test-revert.t.err
@@ -169,20 +169,19 @@
 #if execbit
   $ chmod +x c
   $ hg revert --all
-  reverting c

Maybe that's a general Cygwin problem, as Cygwin's stock Mercurial pack-
age features the same behaviour, as can be seen in:

$ PS4=' $ ' ksh -x ~/scr/test 2>&1
 $ umask 077
 $ export 'HGPLAINEXCEPT=' 'HGRCPATH='
 $ rm -rf repo
 $ /bin/hg init repo
 $ cd repo
/home/Rainer/tmp/repo
 $ touch x
 $ /bin/hg status -A
? x
 $ /bin/hg commit -Am 'Add x'
adding x
 $ ls -l x
-rw------- 1 Rainer win 0 2016-01-28 13:00 x
 $ chmod +x x
 $ ls -l x
-rwx------ 1 Rainer win 0 2016-01-28 13:00 x
 $ /bin/hg status -A
C x
 $ /bin/hg --version
Mercurial Distributed SCM (version 3.5.2)
(see http://mercurial.selenic.com for more information)

Copyright (C) 2005-2015 Matt Mackall and others
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
$

Can this be fixed or is this a Cygwin (or Windows) limitation?   Oh, be-
fore I forget: this is a fairly current Cygwin on Windows Vista 32 Bit:

$ uname -srv
CYGWIN_NT-6.0 2.4.1(0.293/5/3) 2016-01-24 11:24
$

Sincerely,
  Rainer