pyversions.py: fix parsing DEBPYTHON_SUPPORTED env. variable

versions should be separated using comma, as in debian_defaults config file

debian/changelog

@@ -8,6 +8,9 @@ python-defaults (2.7.3-3) UNRELEASED; urgency=low
       python3-* ones
     - TODO: parse interpreter version number from --shebang option and add
       apropriate dependency/rt* script arguments
+  * pyversions.py: fix parsing DEBPYTHON_SUPPORTED env. variable
+    (versions should be separated using comma, as in debian_defaults
+    config file)
 
   [ Dmitry Shachnev ]
   * debian/python.{pre,post}rm.in: Handle purge command the same way as

debian/pyversions.py

@@ -110,8 +110,9 @@ def unsupported_versions(version_only=False):
     else:
         return _unsupported_versions
 
-_supported_versions = ["python%s" % ver for ver in \
-                       os.environ.get('DEBPYTHON_SUPPORTED', '').split()]
+_supported_versions = ["python%s" % ver.strip() for ver in
+                       os.environ.get('DEBPYTHON_SUPPORTED', '').split(',')
+                       if ver.strip()]
 def supported_versions(version_only=False):
     global _supported_versions
     if not _supported_versions: