#12 Spurious reference in macro parameter

[Simon Wright]

In the LaTeX output for this from nuweb.w

@d Copy label from source into
@{{
@<Get label from@(source_get()@)@>
write_label(label_name, @1);
}@}

the PDF output contains

⟨Get label from (38d source get() ) 104a⟩

(the scrap's own label is 38c, the 38d is the problem).