func in command doesn't get exuecuted.

Greetings,

I have a target I want to rebuild everytime I run scons.

so I defined the following command:
env.AlwaysBuild(env.Command(get_target("initial_step"), get_deps("initial_step"), build))

get_target returns the target based on a label, get_deps returns a list of deps based on a label
build is defined as follows:
def build(target, source, env):
    raise NameError('die')

when I run scons like this: scons tar -nQ --tree=all --debug=explain

scons: rebuilding `/tmp/a' because AlwaysBuild() is specified
build(["/tmp/a"], ["/tmp/create_a.sh"])

but no error, the build just continues.

any idea how to debug this issue?

Thanks,

Dagg