pythonlib/script: return debug level also for the first invocation (backport https://trac.osgeo.org/grass/changeset/61272)

git-svn-id: https://svn.osgeo.org/grass/grass/branches/releasebranch_7_0@61680 15284696-431f-4ddb-bdfa-cd5b030d7da7

lib/python/script/core.py

@@ -1707,6 +1707,7 @@ def debug_level():
     _debug_level = 0
     if find_program('g.gisenv', '--help'):
         _debug_level = int(gisenv().get('DEBUG', 0))
+    return _debug_level
 
 
 def legal_name(s):