Fix JENKINS-13566 introduced the following bug.

I can no longer escape the dollar sign value on a Windows environment.

e.g.
foobar1=foo\$bar
foobar2=foo$bar

Respectively becomes:
foo\$bar
foo

The value "foo$bar" cannot be achieved.

My opinion is that the "escaping" behaviour should be the same regardless of operating system. I propose that the JENKINS-13566 changes should be reverted, and that Vincent Latombe should double escape their path.
i.e.
C:\DOCUME~1\\$NCESE~1\LOCALS~1\Temp