Can't reference environment variables for option defaults

[Alex Honor]

I might have an option named --catalina-base and want it defaulted to the environment variable $CATALINA_BASE.

--catalina-base <$CATALINA_BASE>

The option processor resets CATALINA_BASE to the empty string. This effectively eliminates the default value.

The option processor should only initialize the variable to an empty value if it is unset.

[Lee Thompson]

Good catch!