propperly escape paths on windows

[SimonDanisch]

fix one part of the issue in #160

[codecov-io]

Codecov Report

Merging #161 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #161   +/-   ##
=======================================
  Coverage   67.26%   67.26%           
=======================================
  Files          14       14           
  Lines         446      446           
=======================================
  Hits          300      300           
  Misses        146      146

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[shashi]

thanks!