Commit ...

217b8c2e0 * gnu: perl: Replace with 5.26.2 [fixes
CVE-2018-{6797,6798,6913}].

... caused the attached perl script that worked like this ...

g1@g1 ~/.mail-mirror$ guix environment --ad-hoc perl perl-timedate make wget
g1@g1 ~/.mail-mirror [env]$ perl mb2md-3.20.pl
Usage:
       mb2md -h
       mb2md [-c] -m [-d destdir]
       mb2md [-c] -s sourcefile [-d destdir]
       mb2md [-c] -s sourcedir [-l wu-mailboxlist] [-R|-f somefolder] [-d destdir] [-r strip_extension]
g1@g1 ~/.mail-mirror [env]$


... to stop working ...

g1@g1 ~/.mail-mirror$  guix environment --ad-hoc perl perl-timedate make wget
g1@g1 ~/.mail-mirror [env]$  perl mb2md-3.20.pl
Can't locate Date/Parse.pm in @INC (you may need to install the Date::Parse module) (@INC contains: /gnu/store/wpwb4ig3qhv3m7axjlid2c0f1jqzp09p-profile/lib/perl5/site_perl/5.26.2/x86_64-linux-thread-multi /gnu/store/wpwb4ig3qhv3m7axjlid2c0f1jqzp09p-profile/lib/perl5/site_perl/5.26.2 /gnu/store/wpwb4ig3qhv3m7axjlid2c0f1jqzp09p-profile/lib/perl5/site_perl /gnu/store/ynk3rg3i791i6k7rz2imbyj9wyfjrnrc-perl-5.26.2/lib/perl5/site_perl/5.26.2/x86_64-linux-thread-multi /gnu/store/ynk3rg3i791i6k7rz2imbyj9wyfjrnrc-perl-5.26.2/lib/perl5/site_perl/5.26.2 /gnu/store/ynk3rg3i791i6k7rz2imbyj9wyfjrnrc-perl-5.26.2/lib/perl5/5.26.2/x86_64-linux-thread-multi /gnu/store/ynk3rg3i791i6k7rz2imbyj9wyfjrnrc-perl-5.26.2/lib/perl5/5.26.2) at mb2md-3.20.pl line 385.
BEGIN failed--compilation aborted at mb2md-3.20.pl line 385.
g1@g1 ~/.mail-mirror [env]$

TIA - George