Bug 7857 - database upgrade fails with plack

Bug 7857 - database upgrade fails with plack

Updating database structure

Update errors :

    Can't locate C4/Context.pm in @INC (@INC contains: /etc/perl /usr/local/lib/perl/5.10.1 /usr/local/share/perl/5.10.1 /usr/lib/perl5 /usr/share/perl5 /usr/lib/perl/5.10 /usr/share/perl/5.10 /usr/local/lib/site_perl /usr/local/lib/perl/5.10.0 /usr/local/share/perl/5.10.0 .) at /srv/koha/installer/data/mysql/updatedatabase.pl line 37.
    BEGIN failed--compilation aborted at /srv/koha/installer/data/mysql/updatedatabase.pl line 37.

It seems that plack cleans enviroment, so we have to re-instart PERL5LIB
so script invocation won't fail.

It also fixes exit 1 which fail with plack.

Signed-off-by: Paul Poulain <paul.poulain@biblibre.com>