shells/bash-4.0 port horribly broken

[bf]

Hang on guys, we're looking into it.  The upstream maintainer
confirms that failures in command substitutions are _not_ the
expected behavior of bash 4.x, that they are not being observed on
many other systems, and that in the past similar problems like
this have been connected with problems in bison, so maybe our use
of system yacc has something to do with it.

The point about running the testsuite is well-taken.

b.