installing hsdev fails: strip.exe: File exists

It creates executables in \AppData\Roaming\cabal\bin and then strip.exe often fails (but not always) with `File exists` error:

```
Installing library in
C:\Users\voide\AppData\Roaming\cabal\i386-windows-ghc-7.10.3\hsdev-0.1.5.5-6ru4Wp2Xjfd5WeK2d1GhPK
Installing executable(s) in C:\Users\voide\AppData\Roaming\cabal\bin
D:\Programs\ghc\ghc-7.10.3\mingw\bin\strip.exe: невозможно переименовать (can't rename) C:\Users\voide\AppData\Roaming\cabal\bin\hscabal.exe; причина (reason): File exists
Preprocessing executable 'hshayoo' for hsdev-0.1.5.5...
Preprocessing executable 'hsautofix' for hsdev-0.1.5.5...
```

cabal version:

```
cabal-install version 1.22.7.0
using version 1.22.5.0 of the Cabal library
```

Start by reproducing the hsdev installation on Windows with cabal-install 1.22.7.0, Cabal 1.22.5.0, and GHC 7.10.3, focusing on the executable installation and strip.exe step in cabal\bin. Done means the installation completes without the “File exists” rename failure; the issue does not name a source file or test.

Written by the indexing model from the issue text.