Fix path list with whitespace

[asztalosdani]

The packages path is split badly if a path contains whitespace.
If I set REZ_PACKAGES_PATH to c:/foo bar/baz, rez will interpret it as ["c:/foo", "bar/baz"].

This PR fixes this issue. I also made a test to prove this.

[oktomus]

You haven't committed with your github account. You can fix this by doing the following

git config user.email "github email"
git reset [hash of previous commit]
git add 
git commit "Fix path list with whitespace"
git push -f asztalosdani:master

[asztalosdani]

Thank you, I fixed it.

[nerdvegas]

fails on linux (pathsep is :)

[fnaum]

I think it is not a good idea to change an environment variable in the UT as it affects all other tests that are run as part of the same process (i.e when running rez selftests)
This line breaks a test on other unrelated area.
If you really need to, then put the original value back...something along the lines

original_packages_path = os.environ["REZ_PACKAGES_PATH"]
os.environ["REZ_PACKAGES_PATH"] = os.pathsep.join(packages_path)
self.assertEqual(c.packages_path, packages_path)
os.environ["REZ_PACKAGES_PATH"] = original_packages_path

or if you are going to use it several times create a @contextmanager and with with ...

Also, I do not understand the original use case of this change.
Why not set the path like c:/foo;c:/bar/baz or "/foo:baz/bar` why do you need the space?

[mottosso]

Agreed on not changing variables that persist across tests, however:

Why not set the path like c:/foo;c:/bar/baz or "/foo:baz/bar` why do you need the space?

The folder c:\foo bar\ is different from c:\foo and c:\bar I think.

[fnaum]

Would quotes work in this case? ie. "c:\foo bar"?