#
#
# patch "tracvc/mtn/cache.py"
#  from [002c9c78cae717b48ab71dec380935bcccd0c473]
#    to [ee9520b88bf99131896bdb55ec7d977be849ef9f]
#
============================================================
--- tracvc/mtn/cache.py	002c9c78cae717b48ab71dec380935bcccd0c473
+++ tracvc/mtn/cache.py	ee9520b88bf99131896bdb55ec7d977be849ef9f
@@ -147,13 +147,16 @@ Cache.add_backend('localmem', LocalMem)
 # Unfortunately, dbash (i.e. bsddb) doesn't work reliably, at least on
 # my system, so we can't simply use anydb, which prefers dbhash.
 
+try:
+    import shelve
+    import dbm
+except ImportError:
+    dbm = None
+
 class DBMShelve(LocalMem):
     """Using Python's shelve on a DBM database."""
 
     def __init__(self, realm, prefix):
-        import shelve
-        import dbm
-
         self.dbname = prefix + realm
         self.cache = shelve.Shelf(dbm.open(self.dbname, 'c'))
         self.lock = Lock()
@@ -164,9 +167,19 @@ class DBMShelve(LocalMem):
     def flush_all(self):
         self.cache = Shelf(dbm.open(self.dbname, 'n'))
 
-Cache.add_backend('dbmshelve', DBMShelve)
+if dbm:
+    Cache.add_backend('dbmshelve', DBMShelve)
 
 
+has_bsddb = False
+try:
+    from bsddb3 import dbshelve, db
+except ImportError:
+    try:
+        from bsddb import dbshelve, db
+    except ImportError:
+        db = None
+
 class BSDDBShelve(Cache):
     """Using the bsddb3 interface to db."""
 
@@ -175,14 +188,12 @@ class BSDDBShelve(Cache):
     @classmethod
     def get_env(self, dir):
         if not self.dbenv:
-            from bsddb3 import db
             self.dbenv = db.DBEnv()
             self.dbenv.open(dir,
                 db.DB_INIT_CDB|db.DB_INIT_MPOOL|db.DB_CREATE)
         return self.dbenv
 
     def __init__(self, realm, dir, prefix=''):
-        from bsddb3 import dbshelve
         self.dbname = prefix + realm
         self.cache = dbshelve.open(self.dbname, dbenv=self.get_env(dir))
         
@@ -196,7 +207,8 @@ class BSDDBShelve(Cache):
     def get(self, key):
         return self.cache[key]
 
-Cache.add_backend('bsddb', BSDDBShelve)
+if db:
+    Cache.add_backend('bsddb', BSDDBShelve)
 
 
 def memoize(get_cachespec, realm = None):