remove zombie process in file seeking

This was the last one marked as a zombie. There might be others I don't
know about, but except for in the hypothetical case of a thread dying
due to an async exception before it can wait on a process it started, I
don't know of any.

It would probably be safe to remove the reapZombies now, but let's wait
and so that in its own commit in case it turns out to cause problems.

This commit was sponsored by Boyd Stephen Smith Jr. on Patreon.

Git/Command.hs

@@ -55,7 +55,7 @@ runQuiet params repo = withNullHandle $ \nullh ->
  -
  - Also returns an action that should be used when the output is all
  - read, that will wait on the command, and
- - return True if it succeeded. Failure to wait will result in zombies.
+ - return True if it succeeded.
  -}
 pipeReadLazy :: [CommandParam] -> Repo -> IO (L.ByteString, IO Bool)
 pipeReadLazy params repo = assertLocal repo $ do
@@ -134,10 +134,6 @@ pipeNullSplitStrict params repo = do
 	s <- pipeReadStrict params repo
 	return $ filter (not . S.null) $ S.split 0 s
 
-{- Doesn't run the cleanup action. A zombie results. -}
-leaveZombie :: (a, IO Bool) -> a
-leaveZombie = fst
-
 {- Runs a git command as a coprocess. -}
 gitCoProcessStart :: Bool -> [CommandParam] -> Repo -> IO CoProcess.CoProcessHandle
 gitCoProcessStart restartable params repo = CoProcess.start numrestarts "git"