Fix importing of shared libraries from inside packages.
This is a bit of a hack: when the shared library is loaded, the module
name is "package.module", but the module calls Py_InitModule*() with just
"module" for the name.  The shared library loader squirrels away the true
name of the module in _Py_PackageContext, and Py_InitModule*() will
substitute this (if the name actually matches).

Python/modsupport.c

diff --git a/Python/modsupport.c b/Python/modsupport.c
index 854439b..12ecaf6 100644
--- a/Python/modsupport.c
+++ b/Python/modsupport.c
@@ -39,6 +39,9 @@
 typedef double va_double;
 #endif
 
+/* Package context -- the full module name for package imports */
+char *_Py_PackageContext = NULL;
+
 /* Py_InitModule4() parameters:
    - name is the module name
    - methods is the list of top-level functions
@@ -69,6 +72,13 @@
 	if (module_api_version != PYTHON_API_VERSION)
 		fprintf(stderr, api_version_warning,
 			name, PYTHON_API_VERSION, name, module_api_version);
+	if (_Py_PackageContext != NULL) {
+		char *p = strrchr(_Py_PackageContext, '.');
+		if (p != NULL && strcmp(name, p+1) == 0) {
+			name = _Py_PackageContext;
+			_Py_PackageContext = NULL;
+		}
+	}
 	if ((m = PyImport_AddModule(name)) == NULL)
 		return NULL;
 	d = PyModule_GetDict(m);