Re: exec/2,3 spawn process even when error raised (0925)

Some further strange behaviour after the incorrect exec/2 (on Unix, at least):

[eclipse 1]: exec(command, [output,input,error]).
illegal stream mode in exec(command, [output, input, error], _211)
[eclipse 2]: wait(X,Y).

X = 11665
Y = 33280     More? (;) 
yes.
[eclipse 3]: block(exit_block(a), a, writeln(handle-a)).

yes.
Signal 13
Signal 13
output error: Broken pipe in flush(output)
[eclipse 4]: 

The exit_block(a) should be caught by the block and 'handle-a' printed, but
the previous exec seems to interact with this.