Fix the 'index.cache' timestamp check.

Since we're using 'unless' here, we should use (>) instead of (>=).

cabal-install/Distribution/Client/IndexUtils.hs

@@ -240,7 +240,7 @@ whenCacheOutOfDate origFile cacheFile action = do
     else do
       origTime  <- getModificationTime origFile
       cacheTime <- getModificationTime cacheFile
-      unless (cacheTime >= origTime) action
+      unless (cacheTime > origTime) action
 
 
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