eval() of empty string hangs

[Chris Connett]

Peter Hansen wrote:
> 
> As an alternative, and not requiring that you special case
> anything, does it work if you simply append '\n' to the
> string to be eval'ed in all cases?

I did try a number of ways of massaging the input string, though far 
from exhaustive; I tried adding the single newline - it didn't help.

I did however localize the problem more tightly.  It does not seem to be 
eval that's hanging, but raise-ing is not working.  When I tried my 
original plan of special casing '', I added a check for equality, then 
manually raised a SyntaxError.  This exhibited the same behavior.  I 
then tried unconditionally raising SyntaxError, same result.  Is it 
possible that the exception is propagating up the wrong stack?  This is 
a separate thread, could it be on the main thread somehow?  The creating 
thread has ended by the time this exception is due to be raised.  There 
are numerous try-excepts to catch this, all should log at least some 
message, but the log shows nothing.