MDEV-18362 EPOCH=1 needs to be set for Ubuntu 18.10 cosmic builds

Apply dbart's patch to set epoch for all ubuntu releases starting
from bionic. Not only for bionic.

This works for Debian too (VERNUM=unstable, etc).

debian/autobake-deb.sh

@@ -30,6 +30,7 @@ LOGSTRING="MariaDB build"
 # Look up distro-version specific stuff.
 
 CODENAME="$(lsb_release -sc)"
+VERNUM="$(lsb_release -sr)"
 
 # add libcrack2 (>= 2.9.0) as a build dependency
 # but only where the distribution can possibly satisfy it
@@ -57,7 +58,7 @@ sed -i -e "s/\\\${LIBSSL}/${LIBSSL}/g" debian/control
 #
 echo "Incrementing changelog and starting build scripts"
 
-if [[ "$CODENAME" == bionic ]]; then
+if [[ "${VERNUM%.*}" -ge 18 ]]; then
   EPOCH="1:"
 fi
 dch -b -D ${CODENAME} -v "${EPOCH}${UPSTREAM}${PATCHLEVEL}-${RELEASE_NAME}${RELEASE_EXTRA:+-${RELEASE_EXTRA}}1~${CODENAME}" "Automatic build with ${LOGSTRING}."