bug#22713: guix prints stray ^M characters

[Danny Milosavljevic]

There are some stray ^M characters in the (git) guix output:

accepted connection from pid 2640, user dannym
looking for the latest release of GNU gcc...^M                                  
          ^Mguix package: warning: ambiguous package specification `guile'
looking for the latest release of GNU guile...^M                                
              ^MThe following packages would be installed:

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Easiest to see using "less test-suite.log" after there was a test failure.