Given that your back trace contains these lines:

/home/linuxer/perl5/perlbrew/perls/perl-5.20.0/lib/site_perl/5.20.0/x8
+6_64-linux/auto/Unicode/LineBreak/LineBreak.so(gcstring_destroy+0x11)
+[0x7f6a1c3f9de1]
/home/linuxer/perl5/perlbrew/perls/perl-5.20.0/lib/site_perl/5.20.0/x8
+6_64-linux/auto/Unicode/LineBreak/LineBreak.so(+0x611a)[0x7f6a1c3ee11
+a]
[download]

It seems likely that the bug is in Unicode::LineBreak, a module loaded by App::DBBrowser. Are you able to reproduce this bug without Unicode::LineBreak being loaded?

Update: regarding your test on Perl 5.21.0, it is not surprising that you get the same result. Perl 5.21.0 is not substantially different to Perl 5.20.0. From perldelta.pod:

Perl 5.21.0 represents approximately 12 hours of development since Perl 5.20.0 [...]

Perl continues to flourish into its third decade thanks to a vibrant community of users and developers. The following people are known to have contributed the improvements that became Perl 5.21.0:

Nicholas Clark, Ricardo Signes.

The only significant change between 5.20.0 and 5.21.0 was to remove some of the modules that were deprecated in 5.20.0.