export PYTHON_EXEC if it wasn't set already; otherwise os.environ["PYTHON_PATH"] will throw an exception

git-svn-id: svn://bind10.isc.org/svn/bind10/branches/f2f200910@288 e5f2f494-b856-4b98-b285-d166d9295462

src/bin/bind10/bind10.in

@@ -1,6 +1,8 @@
 #! /bin/sh
 
 PYTHON_EXEC=${PYTHON_EXEC:-/usr/bin/python3.0}
+export PYTHON_EXEC
+
 BIND10_PATH=@abs_top_srcdir@/src/bin/bind10
 
 PATH=@abs_top_srcdir@/src/bin/msgq:@abs_top_srcdir@/src/bin/parkinglot:@abs_top_srcdir@/src/bin/bind-cfgd:$PATH