Thread by forkIO freezes (while read :: Int if error appears) when compiled with -threaded option
I attached program to reproduce bug.
While running you need type "abc" then "1":
1. if build with "ghc -threaded concbug.hs" - code after "threadDelay_ t" on 29 is never run.
1. if build as "ghc concbug.hs" - program work as expected
<details><summary>Trac metadata</summary>
| Trac field | Value |
| ---------------------- | ------------ |
| Version | 7.10.3 |
| Type | Bug |
| TypeOfFailure | OtherFailure |
| Priority | normal |
| Resolution | Unresolved |
| Component | Compiler |
| Test case | |
| Differential revisions | |
| BlockedBy | |
| Related | |
| Blocking | |
| CC | |
| Operating system | |
| Architecture | |
</details>
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