[master] python nested dlopen fix

src/lib/python/isc/datasrc/__init__.py

 import sys
 import os
 
+# The datasource factory loader uses dlopen, as does python
+# for its modules. Some dynamic linkers do not play nice if 
+# modules are not loaded with RTLD_GLOBAL, a symptom of which
+# is that exceptions are not recognized by type. So to make
+# sure this doesn't happen, we temporarily set RTLD_GLOBAL
+# during the loading of the datasource wrappers.
+import ctypes
+flags = sys.getdlopenflags()
+sys.setdlopenflags(flags | ctypes.RTLD_GLOBAL)
+
 # this setup is a temporary workaround to deal with the problem of
 # having both 'normal' python modules and a wrapper module
 # Once all programs use the new interface, we should remove the
@@ -16,6 +26,10 @@ if intree:
     from datasrc import *
 else:
     from isc.datasrc.datasrc import *
+
+# revert to the default dlopen flags
+sys.setdlopenflags(flags)
+
 from isc.datasrc.sqlite3_ds import *
 from isc.datasrc.master import *