Only look for Nexus username/password during task execution.
Only look for Nexus username/password during task execution.

If the Nexus username and password aren't available when we run a task that needs them, we want the build to fail.
Previously, however, ALL build tasks were failing when the properties were missing, even ones that have nothing to do with Nexus.

Unidata/netcdf-java,Unidata/netcdf-java,Unidata/netcdf-java,Unidata/netcdf-java,Unidata/netcdf-java,Unidata/netcdf-java,Unidata/netcdf-java