SF patch #471839: Bug when extensions import extensions (Shane Hathaway)

    When an extension imports another extension in its
    initXXX() function, the variable _Py_PackageContext is
    prematurely reset to NULL. If the outer extension then
    calls Py_InitModule(), the extension is installed in
    sys.modules without its package name. The
    manifestation of this bug is a "SystemError:
    _PyImport_FixupExtension: module <package>.<extension>
    not loaded".

    To fix this, importdl.c just needs to retain the old
    value of _Py_PackageContext and restore it after the
    initXXX() method is called. The attached patch does this.

    This patch applies to Python 2.1.1 and the current CVS.

Python/importdl.c

@@ -22,7 +22,7 @@ PyObject *
 _PyImport_LoadDynamicModule(char *name, char *pathname, FILE *fp)
 {
 	PyObject *m, *d, *s;
-	char *lastdot, *shortname, *packagecontext;
+	char *lastdot, *shortname, *packagecontext, *oldcontext;
 	dl_funcptr p;
 
 	if ((m = _PyImport_FindExtension(name, pathname)) != NULL) {
@@ -48,9 +48,10 @@ _PyImport_LoadDynamicModule(char *name, char *pathname, FILE *fp)
 			     shortname);
 		return NULL;
 	}
+        oldcontext = _Py_PackageContext;
 	_Py_PackageContext = packagecontext;
 	(*p)();
-	_Py_PackageContext = NULL;
+	_Py_PackageContext = oldcontext;
 	if (PyErr_Occurred())
 		return NULL;
 	if (_PyImport_FixupExtension(name, pathname) == NULL)