有人可以解释为什么stack setup 7.10.3只会安装7.10.2吗？
john@john-3-11:~$ stack setup 7.10.3
Already downloaded.
Installed GHC.
Would add the following to PATH: /home/john/.stack/programs/x86_64-linux/ghc-7.10.2/bin
john@john-3-11:~$ ls /home/john/.stack/programs/x86_64-linux/
ghc-7.10.2 ghc-7.10.2.installed ghc-7.10.2.tar.xz
这是一个问题，因为我正在尝试安装iHaskell：
john@john-3-11:~$ stack install ihaskell-0.8.3.0
Using resolver: lts-5.0 from global config file: /home/john/.stack/global/stack.yaml
GHC version mismatched, found 7.10.2 (x86_64), but expected version 7.10.3 (x86_64) (based on resolver setting in /home/john/.stack/global/stack.yaml). Try running stack setup
我以另一种方式安装了7.10.3 ......它位于我的计算机/opt/ghc/7.10.3的不同部分，所以现在有两种不同版本的GHC浮动。而对于某些进一步的混淆，which指向我在堆栈中安装的版本：
john@john-Lenovo-Yoga-3-11:~$ which ghc
/home/john/.stack/programs/x86_64-linux/ghc-7.10.2/bin/ghc
为什么不能首先安装7.10.3？至少我可以告诉stack我把它放在哪里。
$ stack setup -v
Version 0.1.2.0
2016-01-27 21:31:16.546277: [debug] Checking for project config at: /home/john/stack.yaml @(stack-0.1.2.0:Stack.Config src/Stack/Config.hs:496:9)
2016-01-27 21:31:16.546422: [debug] Checking for project config at: /home/stack.yaml @(stack-0.1.2.0:Stack.Config src/Stack/Config.hs:496:9)
2016-01-27 21:31:16.546482: [debug] Checking for project config at: /stack.yaml @(stack-0.1.2.0:Stack.Config src/Stack/Config.hs:496:9)
2016-01-27 21:31:16.546533: [debug] No project config file found, using defaults. @(stack-0.1.2.0:Stack.Config src/Stack/Config.hs:523:13)
2016-01-27 21:31:16.547163: [info] Using resolver: lts-5.0 from global config file: /home/john/.stack/global/stack.yaml @(stack-0.1.2.0:Stack.Config src/Stack/Config.hs:302:32)
2016-01-27 21:31:16.557306: [debug] Run process: ghc --info @(stack-0.1.2.0:System.Process.Read src/System/Process/Read.hs:254:3)
2016-01-27 21:31:16.594867: [debug] Performing a sanity check on: /usr/bin/ghc @(stack-0.1.2.0:Stack.Setup src/Stack/Setup.hs:754:5)
2016-01-27 21:31:16.595008: [debug] Run process: ghc /tmp/stack-sanity-check11387/Main.hs -no-user-package-db @(stack-0.1.2.0:System.Process.Read src/System/Process/Read.hs:254:3)
2016-01-27 21:31:16.905181: [info] GHC on PATH would be used @(main:Main src/main/Main.hs:439:30)