build error: WARNING: 'aclocal-1.14' is missing on your system

Building from source fails with:

dh_auto_build
make -j1
make[2]: Entering directory '/tmp/source_copy/tre'
CDPATH="${ZSH_VERSION+.}:" && cd . && /bin/bash /tmp/source_copy/tre/utils/missing aclocal-1.14 -I m4
/tmp/source_copy/tre/utils/missing: line 81: aclocal-1.14: command not found
WARNING: 'aclocal-1.14' is missing on your system.
         You should only need it if you modified 'acinclude.m4' or
         'configure.ac' or m4 files included by 'configure.ac'.
         The 'aclocal' program is part of the GNU Automake package:
         <http://www.gnu.org/software/automake>
         It also requires GNU Autoconf, GNU m4 and Perl in order to run:
         <http://www.gnu.org/software/autoconf>
         <http://www.gnu.org/software/m4/>
         <http://www.perl.org/>
make[2]: *** [aclocal.m4] Error 127
Makefile:434: recipe for target 'aclocal.m4' failed
make[2]: Leaving directory '/tmp/source_copy/tre'
dh_auto_build: make -j1 returned exit code 2
debian/rules:14: recipe for target 'override_dh_auto_build' failed
make[1]: Leaving directory '/tmp/source_copy/tre'
make[1]: *** [override_dh_auto_build] Error 2
debian/rules:3: recipe for target 'build' failed
make: *** [build] Error 2
dpkg-buildpackage: error: debian/rules build subprocess returned exit status 2

so it cannot be built on bionic. We changed the command to 'aclocal-1.15' which fixed the issue.