aspell-0.50.3-14 doesn't have ispell in the default search path, it's in
/usr/share/aspell/ispell, which means that Emacs, which sets ispell-program-name
to "ispell", can't find it.
I'm guessing that aspell, rather than emacs, should be modified here, but if you
disagree, feel free to reassign this bug to the emacs component :-).
have you tried -15? it moves ispell from /usr/share/aspell to /usr/bin