-INT_MIN/-1 => signed overflow exception

[Pádraig Brady]

Happens on x86_64 with 4.2.10(1) and 4.2.42(2) at least

The following (done in a subshell to avoid killing the current shell) 
demonstrates it:

$ ($((-2**63/-1)))
Floating point exception (core dumped)

thanks,
Pádraig.