That indeed is a bug. I will fix that.
Currently you can't really avoid it except for using the old -vardef parameter.
Alternatively you could add the variables to the connection profile you are using.
http://www.sql-workbench.net/manual/profiles.html#profile-variables
The easiest way to do that is to use the property file based profiles:
http://www.sql-workbench.net/manual/plain-profile-file.html
And then add something like this to the .properties file:
profile.0001.connection.variables=<properties><entry key="var_id">42</entry><entry key="person_name">Dent</key></properties>
Or you use the GUI to define the connection profile and re-use that profile from the command line.
Thanks for the feedback
Thomas