No failure code when install fails with pre-existing build directory

[wolever]

For example:

$ mkdir build
$ mkdir build/fish
$ pip install -b build fish
Downloading/unpacking fish

pip can't proceed with requirement 'fish' due to a pre-existing build directory.
 location: /Users/wolever/code/sandbox/build/fish
This is likely due to a previous installation that failed.
pip is being responsible and not assuming it can delete this.
Please delete it and try again.

Cleaning up...
$ echo $?
0
$ pip --version
pip 1.4.1 from /path/to/virtualenv

This is… is a bit of a problem when pip is run from scripts :\

[qwcode]

this was fixed in develop branch recently (for the unreleased v 1.5) See pull #1162
Feel free to confirm that fix.