possibly incorrect indentation or mismatched brackets

I'm having a weird problem. This code compiles:

fetchSomething :: IO String
fetchSomething = return "Something"

main :: IO ()
main = do
    if True
        then do
            l <- fetchSomething
            let fn s = do
                let rs = s ++ ": "
                l <- fetchSomething
                return $ rs ++ l
            n <- fn "Prefix"
            putStr n
        else return ()

but the following doesn't:

    let ep = Bridge.destination b </> e
    ed <- doesDirectoryExist ep
    if ed 
        then do
            ds <- listDirs ep
            let fn p = do
                let t = readUTC p
                lt <- toLocalTime t               <-- parse error (possibly incorrect indentation or mismatched brackets)
                return $ Snapshot t lt e b 
            l <- mapM fn ds
            let r = sortBy (compare `on` time) l
            let ri = Prelude.take m $ assignIDs 1 r
            if o == Oldest
                then return $ ri
                else return $ reverse ri
        else return []

Here's a live demo of the former: http://coliru.stacked-crooked.com/a/0305f546c8566683

To test the second, the only way I could find is by downloading this repository: https://github.com/Jefffrey/Kopia/commit/9ec9eb93183c4ceed6d324f7fc726584de02755c and running cabal test.

Someone on the #haskell channel reproduced it on his machine too.

This seems like a bug.

Trac metadata

Trac field	Value
Version	7.6.3
Type	Bug
TypeOfFailure	OtherFailure
Priority	low
Resolution	Unresolved
Component	Compiler
Test case
Differential revisions
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