IFileSystem.fileExists returns false even when a file exists.

[DonJayamanne]

This breaks conda and virtual environments

• These environments are no longer listed as interpreters, hence absolutely nothing works for conda or virtual environments.

In master.
I believe the logic of checking the file stat is incorrect.
We're checking if the file type == FIle when checking if a file exists.
However fstat could indicate that its a symbolic link.

Not sure this is the issue, but likely. Either way still is incorrect.

I.e. I don't think we should be comparing == File, we might want to check if !== Directory instead. I.e. allow other values except directory. I.e. its possible Unknown could be returned for a file (just as with symbolic links & others).

Proposed solution

• If checking for a file, then ensure fstat !== direcrtory
• If checking for a directory, then ensure fstat !== file

[DonJayamanne]

The problem is we're treating the FileType as an enum and comparing ===.
However these are bit values and we need to use bitwise operations.