Subject: Re: [bug#27355] [PATCH 1/7] gnu: Add libzip.

From: Danny Milosavljevic <[email-masked]>
Date: Thu, 15 Jun 2017 14:33:52 +0200

> +     `(#:phases
> +       (modify-phases %standard-phases
> +         (add-before 'configure 'patch-perl
> +           (lambda _
> +             (substitute* "regress/runtest.in"
> +               (("/usr/bin/env perl") (which "perl"))))))))
> +    (inputs
> +     `(("perl" ,perl)

Hmm.  Sounds like perl is used for regression tests.  Is it used in the derivation?