[PATCH 2 of 4 v2] tests: use debuginstall to retrieve hg version

[timeless]

# HG changeset patch
# User timeless <timeless at mozdev.org>
# Date 1462920746 0
#      Tue May 10 22:52:26 2016 +0000
# Node ID ed9fa9c2af2c37a9273d1f20c96f4acb45733fe6
# Parent  2ab114fef14fd6d1ef109043e9300b015b0c0e2f
# EXP-Topic runtests
# Available At bb://timeless/mercurial-crew
#              hg pull bb://timeless/mercurial-crew -r ed9fa9c2af2c
tests: use debuginstall to retrieve hg version

diff -r 2ab114fef14f -r ed9fa9c2af2c tests/test-extension.t
--- a/tests/test-extension.t	Tue May 10 22:45:45 2016 +0000
+++ b/tests/test-extension.t	Tue May 10 22:52:26 2016 +0000
@@ -958,7 +958,7 @@
   ** Extensions loaded: throw, older
 
 Declare the version as supporting this hg version, show regular bts link:
-  $ hgver=`$PYTHON -c 'from mercurial import util; print util.version().split("+")[0]'`
+  $ hgver=`hg debuginstall -T '{hgver}'`
   $ echo 'testedwith = """'"$hgver"'"""' >> throw.py
   $ if [ -z "$hgver" ]; then
   >   echo "unable to fetch a mercurial version. Make sure __version__ is correct";