Fix NSURLErrorDomain error -999.

Since networking isn't always up when we refresh a list in -viewWillAppear:, we
also refresh when network reachability changes. If this happens quick enough,
we could end up refreshing a second time before the first refresh is done. Now
we only refresh on reachability changes if we're not already refreshing.

Source/UIKit and Foundation/AwfulFetchedTableViewController.m

@@ -27,7 +27,7 @@ @implementation AwfulFetchedTableViewController
 
 - (void)reachabilityChanged:(NSNotification *)note
 {
-    if ([self refreshOnAppear]) [self refresh];
+    if (!self.refreshing && [self refreshOnAppear]) [self refresh];
 }
 
 - (void)viewDidLoad