why is re-defining register names specially treated in gas

[Jan Beulich]

In assign_symbol(), the error for re-defining an already defined symbol
is suppressed when the symbol is in reg_section. Can anyone explain why
this has to be that way? It would seem to me that this is OK for 'real'
register names (i.e. those produced by target specific code) but not for
those resulting from equating custom symbols to register names (which
currently appear to be indistinguishable).

Thanks, Jan