bugfix: lib/sql.py: parse_exception(): make_DuplicateKeyException(): handle nested exceptions (which should never be generated, but may be in case of sql.py bugs such as wiki.vegpath.org/To_Do#Fixes > #1) by printing the nested exception and then rethrowing the original exception, so that the original exception does not get lost and still ends up at the end of the program's output, to enable debugging