issue #6: don't call enable_load_extension unless there are extensions to load. this makes the adapter work on Mac OS.

Author: codeforkjeff

README.md

@@ -102,6 +102,11 @@ make
 This will create `digest.so`. Point to it in your profile config as shown in the
 example above.
 
+Mac OS seems to ship with [SQLite libraries that do not have support for loading extensions compiled in](https://docs.python.org/3/library/sqlite3.html#f1),
+so this won't work "out of the box." Accordingly, snapshots won't work.
+If you need snapshot functionality, you'll need to compile SQLite/python
+or find a python distribution for Mac OS with this support.
+
 ## Development Notes / TODOs
 
 ...

dbt/adapters/sqlite/connections.py

@@ -58,9 +58,11 @@ def open(cls, connection):
             else:
                 raise FailedToConnectException("at least one schema must be called 'main'")
 
-            handle.enable_load_extension(True)
-
             extensions = [e for e in (connection.credentials.extensions or "").split(";") if e]
+
+            if len(extensions) > 0:
+                handle.enable_load_extension(True)
+
             for ext_path in extensions:
                 handle.load_extension(ext_path)