Fixes errors like:

Caught exception in engine "Wide character in syswrite at /nix/store/498lwsrn5kkdh1q8kn3vcpd3457w6m7a-hydra-perl-deps/lib/perl5/site_perl/5.16.3/Starman/Server.pm line 547."

Note that these errors didn't happen if the database encoding was set to SQL_ASCII (which was the case for hydra.nixos.org, explaining why it didn't get these errors). However, now the encoding must be UTF8. To change it, do:

update pg_database set encoding = pg_char_to_encoding('UTF8') where datname = 'hydra';