[PATCH 2 of 2] test-pushvars: invoke shell script hook via `sh` for Windows

[Matt Harbison]

# HG changeset patch
# User Matt Harbison <matt_harbison at yahoo.com>
# Date 1502764008 14400
#      Mon Aug 14 22:26:48 2017 -0400
# Node ID 26abdd16d4b9e91989aa1fce9a01030be4a42840
# Parent  1a077f01241b6256728751b00c552652d024c907
test-pushvars: invoke shell script hook via `sh` for Windows

Invoking *.sh on Windows leads to the "what program should open this?" prompt,
which stalls the test and led to the recent series of exceptions on the Windows
test machine as the runner times out.

diff --git a/tests/test-pushvars.t b/tests/test-pushvars.t
--- a/tests/test-pushvars.t
+++ b/tests/test-pushvars.t
@@ -8,10 +8,9 @@
   > env | egrep "^HG_USERVAR_(DEBUG|BYPASS_REVIEW)" | sort
   > exit 0
   > EOF
-  $ chmod +x $TESTTMP/pretxnchangegroup.sh
   $ cat >> $HGRCPATH << EOF
   > [hooks]
-  > pretxnchangegroup = $TESTTMP/pretxnchangegroup.sh
+  > pretxnchangegroup = sh $TESTTMP/pretxnchangegroup.sh
   > [experimental]
   > bundle2-exp = true
   > EOF