That check-in has been backed out.
1. The change only worked for unix, not Windows. Such asymmetry, while
occasionally necessary, is unwelcomed.
2. There are corner cases where it does not work on unix either.
And those corner cases would be difficult to fix.
3. We don't see a compelling need for this feature (there are better
ways to accomplish the same thing) and so we do not want to risk
the stability of the project in order to implement it.