Relativ paths does not work for Windows

[dmatuschek]

We use this package for a project and we discovered a bug for Windows users. If you want to install dependencies on windows you will receive an OSError - File not found.

We looked a bit deeper into this bug and found out that the path to the python binary (on windows \.venv\Scripts\python.exe) is passed as a relative path. The problem is that Popen on windows does not execute this path from the current working directory (see: https://stackoverflow.com/a/21412727).

Therefore the argument for the Popen call needs to have an absolute path. This could be fixed with (if path contains the absolute path)

@property
def _python_rpath(self):
    """The relative path (from environment root) to python."""
    # Windows virtualenv installation installs pip to the [Ss]cripts
    # folder. Here's a simple check to support:
    if sys.platform == 'win32':
        return os.path.join(self.path, 'Scripts', 'python.exe')
    return os.path.join('bin', 'python')

Alternatively, it could be solved with a os.path.abspath for Windows.

[madhavajay]

@sjkingo ? Any chance of merging this?

For anyone else, thank god for monkeypatching.

from virtualenvapi.manage import VirtualEnvironment
def fix_windows_virtualenv_api(cls):
    def _python_rpath(self):
        """The relative path (from environment root) to python."""
        # Windows virtualenv installation installs pip to the [Ss]cripts
        # folder. Here's a simple check to support:
        if sys.platform == 'win32':
            # fix here https://github.com/sjkingo/virtualenv-api/issues/47
            return os.path.join(self.path, 'Scripts', 'python.exe')   
        return os.path.join('bin', 'python')

    setattr(cls, "_python_rpath", property(_python_rpath))

fix_windows_virtualenv_api(VirtualEnvironment)