do not remove potentially inflight keys from availableKeys

Using all keys from estimated data + all keys from all operation sets
instead.

Author: kashif

Parse/PFObject.m

@@ -2320,12 +2320,21 @@ - (void)removeObjectForKey:(NSString *)key {
 - (void)revert {
     @synchronized (lock) {
         if ([self isDirty]) {
+            NSMutableArray *removedKeys = [NSMutableArray array];
+            [removedKeys addObjectsFromArray: [self allKeys]];
+            for (PFOperationSet *operationSet in operationSetQueue) {
+                for (NSString *key in operationSet.keyEnumerator) {
+                    [removedKeys addObject:key];
+                }
+            }
+            
             PFOperationSet *changes = [self unsavedChanges];
             for (NSString *key in changes.keyEnumerator) {
                 [changes removeObjectForKey:key];
             }
+            
             [self rebuildEstimatedData];
-            [_availableKeys removeAllObjects];
+            [_availableKeys minusSet:[NSSet setWithArray:removedKeys]];
             [self checkpointAllMutableContainers];
         }
     }