Program fails to handle server side errors

dbf2mysql version 1.14a-3.1build1 as packaged on lucid run against MySQL 5.x database does not report server side errors to the user.
Noted that source code for 1.14a-3.1build2 on precise does not differ (only change is update to changelog regarding linking against updated library).

Steps to reproduce problem:
1. Take any available dbf file which has a field which is unique within the records (candidate key)
2. Use dbf2mysql to import the table into a database
3. Use mysql client alter the table to make the identified candidate key into a primary key
        ALTER TABLE test CREATE CONSTRAINT PRIMARY KEY (key)
4. Use dbf2mysql with -vvv to re-import the same file

Actual behaviour:
Program claims to be inserting records, but no additional records will be inserted

Expected behaviour:
Program should report Unique constraint violation for every record processed

Error arises because code assumes that mysql_query returns 0 for OK and -1 for error; according to documentation it returns 0 for OK and non-zero for error.