I was trying to install Twisted on my son's OLPC.  Twisted comes with a
handful of C extensions which are all optional and most of which are not
expected to compile on this platform anyway (they are platform-specific
for Mac or Windows).  If my son's OLPC had a C compiler installed, then
it would attempt to build those modules, fail, and proceed to install
Twisted.  However, since it doesn't have a C compiler, then instead it
stops with an error.

It would be nice if Twisted could tell distutils to try to build a
module, and report whether the build succeeded, but don't stop the
entire setup().

http://twistedmatrix.com/trac/ticket/3586