windows: don't consider '$$' to be an escaped '$' when translating to cmd.exe
This functionality was inherited from `os.path.expandvars()`. But the point of
adding this translating code is to be able to write a portable hook, and bash
wouldn't replace '$$' with '$'. Escaping with '\' works, and is portable.
$ hg init a
$ cd a
$ hg init b
$ echo x > b/x
Should print nothing:
$ hg add b
$ hg st
$ echo y > b/y
$ hg st
Should fail:
$ hg st b/x
abort: path 'b/x' is inside nested repo 'b'
[255]
$ hg add b/x
abort: path 'b/x' is inside nested repo 'b'
[255]
Should fail:
$ hg add b b/x
abort: path 'b/x' is inside nested repo 'b'
[255]
$ hg st
Should arguably print nothing:
$ hg st b
$ echo a > a
$ hg ci -Ama a
Should fail:
$ hg mv a b
abort: path 'b/a' is inside nested repo 'b'
[255]
$ hg st
$ cd ..