Only initialize default DB when no db is passed

Having the default parameter in the parameter list always initializes
the class. That's not what we want here since it actually create a real
database when running the tests.
Signed-off-by: Florian Pritz <bluewind@xinu.at>

upload_pkg_internetarchive.py

@@ -21,10 +21,12 @@ class ArchiveUploader:
     See the <a href="https://wiki.archlinux.org/index.php/Arch_Linux_Archive">Arch Linux Archive documentation</a> for details.
     """
 
-    def __init__(self, internetarchive = ia, db = DB.DB('archive-uploader.sqlite')):
+    def __init__(self, internetarchive = ia, db = None):
         self.ia = internetarchive
         self.db = db
         self.chunksize = 20
+        if self.db is None:
+            self.db = DB.DB('archive-uploader.sqlite')
 
     def clean_name(self, name):
         """Remove chars that are not allowed in an Internet Archive identifier: @.+