expand the relative path for envdir to the full path

tox is passing a relative directory, but the script wants a full path
in some cases.

Author: dhellmann

tests/run_tests

@@ -1,7 +1,7 @@
 # -*- mode: shell-script -*-
 #set -x
 
-envdir="$1"
+envdir="$(cd $1 && pwd)"
 shift
 scripts="$*"
 if [ -z "$scripts" ]