connection: Return copys of cached object lists

Incase any users manipulate the lists, we don't want that to affect
our caching. Could prevent future mistakes

tests/utils.py

@@ -93,20 +93,20 @@ def openconn(uri):
     cache = _conn_cache[uri].copy()
 
     def cb_fetch_all_guests():
-        return cache["vms"]
+        return cache["vms"][:]
 
     def cb_fetch_all_nodedevs():
-        return cache["nodedevs"]
+        return cache["nodedevs"][:]
 
     def cb_fetch_all_pools():
         if "pools" not in cache:
             cache["pools"] = conn._fetch_all_pools_raw()
-        return cache["pools"]
+        return cache["pools"][:]
 
     def cb_fetch_all_vols():
         if "vols" not in cache:
             cache["vols"] = conn._fetch_all_vols_raw()
-        return cache["vols"]
+        return cache["vols"][:]
 
     def cb_clear_cache(pools=False):
         if pools:

virtinst/connection.py

@@ -190,7 +190,7 @@ class VirtualConnection(object):
         key = self._FETCH_KEY_GUESTS
         if key not in self._fetch_cache:
             self._fetch_cache[key] = self._fetch_all_guests_raw()
-        return self._fetch_cache[key]
+        return self._fetch_cache[key][:]
 
     def _fetch_all_pools_raw(self):
         ignore, ignore, ret = pollhelpers.fetch_pools(
@@ -208,7 +208,7 @@ class VirtualConnection(object):
         key = self._FETCH_KEY_POOLS
         if key not in self._fetch_cache:
             self._fetch_cache[key] = self._fetch_all_pools_raw()
-        return self._fetch_cache[key]
+        return self._fetch_cache[key][:]
 
     def _fetch_all_vols_raw(self):
         ret = []
@@ -239,7 +239,7 @@ class VirtualConnection(object):
         key = self._FETCH_KEY_VOLS
         if key not in self._fetch_cache:
             self._fetch_cache[key] = self._fetch_all_vols_raw()
-        return self._fetch_cache[key]
+        return self._fetch_cache[key][:]
 
     def _fetch_all_nodedevs_raw(self):
         ignore, ignore, ret = pollhelpers.fetch_nodedevs(
@@ -257,7 +257,7 @@ class VirtualConnection(object):
         key = self._FETCH_KEY_NODEDEVS
         if key not in self._fetch_cache:
             self._fetch_cache[key] = self._fetch_all_nodedevs_raw()
-        return self._fetch_cache[key]
+        return self._fetch_cache[key][:]
 
 
     #########################