Makefiles in 2.x use unsafe shell construct that can lead to infinite recursion

[James Westby]

Hi,

I set CDPATH in my zsh shell, and somehow this caused off behaviour in /bin/sh (dash)
when building mailman 2.x.

It somehow stopped "cd $$d" from working when run from a Mailman makefile. While this
was a problem with my environment, the build system's behaviour in the face of it isn't very
nice.

As the Makefiles use

  (cd $$d; make)

if the cd fails, they run the make anyway, which causes infinite recursion.

If this was changed to

  (cd $$d && make)

or

  (make -C $$d)

then this wouldn't happen and you would get an error message, rather than
thrashing.

Thanks,

James