76f8b3c5d8a33e5031cb1762096a5f42f75fd6e6
braney
  Wed Feb 24 12:24:32 2016 -0800
address #16850

diff --git src/hg/lib/cart.c src/hg/lib/cart.c
index d5856c1..dde5943 100644
--- src/hg/lib/cart.c
+++ src/hg/lib/cart.c
@@ -760,34 +760,36 @@
 setUdcTimeout(cart);
 if (cartVarExists(cart, hgHubDoDisconnect))
     doDisconnectHub(cart);
 
 pushWarnHandler(cartHubWarn);
 char *newDatabase = hubConnectLoadHubs(cart);
 popWarnHandler();
 
 #ifndef GBROWSE
 if (didSessionLoad)
     cartCopyCustomTracks(cart);
 #endif /* GBROWSE */
 
 if (newDatabase != NULL)
     {
-    // this is some magic to use the defaultPosition */
-    char *oldDb = cartOptionalString(cart, "db");
-    if (oldDb != NULL)
-        hashAdd(oldVars, "db", oldDb);
+    // this is some magic to use the defaultPosition and reset cart variables
+    struct hashEl *hel;
+    if ((hel = hashLookup(oldVars,"db")) != NULL)
+        hel->val = "none";
+    else
+        hashAdd(oldVars, "db", "none");
     cartSetString(cart,"db", newDatabase);
     }
 
 if (exclude != NULL)
     {
     while ((ex = *exclude++))
 	cartExclude(cart, ex);
     }
 
 cartDefaultDisconnector(&conn);
 
 if (didSessionLoad)
     cartHideDefaultTracks(cart);
 return cart;
 }