There are two severe problems with bugzilla-4.2-1.mga2 + one improvement available:

1) In Bugzilla/Constants.pm line 617, bz_locations() contains this line:

  $datadir = "$libpath/$datadir";

but $libpath is not defined at this point, because Mageia harcoded some paths and so removed the definition of $libpath. This line must simply go away; $datadir is already defined at the top of the method.

2) checksetup.pl doesn't load Bugzilla.pm and so the fake Bugzilla.pm located at /usr/lib/perl5/site_perl/5.14.2/Bugzilla.pm is not called. This prevents checksetup.pl from running. This is a regression as the previous 4.0.x RPM had this problem fixed. For checksetup.pl, you must manually fix

  use lib (. lib);

to also include /usr/share/bugzilla/lib.

3) There is an updated version of the fake Bugzilla.pm file available at https://bug679965.bugzilla.mozilla.org/attachment.cgi?id=599392 which is cleaner than the previous version (the one currently included in the RPM). Take care to fix BZ_LIB_DIR and make it point to BZ_ROOT_DIR; Mageia excluded install-module.pl from the RPM and so there is no additional lib/ directory.