InitFS: factor out migration lookup code
InitFS: factor out migration lookup code

Ignore-this: 9203832b376042f5b24f7c465205701

darcs-hash:20090529061633-e018d-d99a52aa4d9f2462ae39c063a209dd0f4b12d4d4.gz

jakubfijalkowski/dbmigrations,nick0x01/dbmigrations,nathankot/dbmigrations,creswick/dbmigrations,anton-dessiatov/dbmigrations