Avoid duplicate relative tracker homes when reinitialising.

diff -r 59de7ad827e2 roundup/admin.py
--- a/roundup/admin.py	Tue May 15 12:38:36 2012 +0200
+++ b/roundup/admin.py	Tue May 15 13:55:54 2012 -0400
@@ -508,7 +508,7 @@
             tracker.nuke()
 
             # re-write the backend select file
-            init.write_select_db(tracker_home, backend, tracker.config.DATABASE)
+            init.write_select_db('.', backend, tracker.config.DATABASE)
 
         # GO
         tracker.init(password.Password(adminpw, config=tracker.config))