imposm-psqldb fails at createlang when plpgsql already exists

[kc2zgu]

Recent postgres versions seem to enable the plpgsql language automatically on creating a new database. This makes the createlang call in the script produced by imposm-psqldb fail since the language already exists, causing the entire script to exit because f set -e.

Something like 'createlang -l ${dbname} |grep plpgsql || createlang plpgsql ${dbname}' should work to check if plpgsql is already enabled (-l lists all currently installed languages) and skip the createlang if necessary.