Fix bug introduced in revision 58385.  Database keys could no longer
have NULL bytes in them.  Replace the errant strdup with a
malloc+memcpy.  Adds a unit test for the correct behavior.
diff --git a/Modules/_bsddb.c b/Modules/_bsddb.c
index f9bc253..d03f72b 100644
--- a/Modules/_bsddb.c
+++ b/Modules/_bsddb.c
@@ -335,11 +335,13 @@
          * the code check for DB_THREAD and forceably set DBT_MALLOC
          * when we otherwise would leave flags 0 to indicate that.
          */
-        key->data = strdup(PyString_AS_STRING(keyobj));
+        key->data = malloc(PyString_GET_SIZE(keyobj));
         if (key->data == NULL) {
             PyErr_SetString(PyExc_MemoryError, "Key memory allocation failed");
             return 0;
         }
+        memcpy(key->data, PyString_AS_STRING(keyobj),
+               PyString_GET_SIZE(keyobj));
         key->flags = DB_DBT_REALLOC;
         key->size = PyString_GET_SIZE(keyobj);
     }
@@ -5795,6 +5797,10 @@
     ADD_INT(d, DB_NOPANIC);
 #endif
 
+#ifdef DB_REGISTER
+    ADD_INT(d, DB_REGISTER);
+#endif
+
 #if (DBVER >= 42)
     ADD_INT(d, DB_TIME_NOTGRANTED);
     ADD_INT(d, DB_TXN_NOT_DURABLE);