Since I just noticed this and haven't seen it mentioned already: for the record, the Python Makefile for current versions is affected by this issue.  The "sharedmods" target, which calls setup.py to build the standard library shared modules, explicitly passes into Distutils via shell variables values for CC, LDSHARED, and OPT.  Unfortunately, as noted in this issue, Distutils does not look for an OPT variable.  So, while CC and LDSHARED can be overridden from the make command with either macro arguments or env vars, OPT cannot: only the value determined at configure time will be used.

I think that Chris's original distutils_opt_flag.patch should be applied to allow OPT to be overridden, without changing any other current behavior.  AFAICT, the only compatibility issue would be if a script happened to already have an OPT env variable defined which would now get used by Distutils. I think the risks of that are pretty small and, in case, much smaller than the more extensive tweaking of Distutils behavior as is done in the Debian patches.

My interest in this comes from discovering that the OS X installer build script has been overriding OPT for its own purposes, thereby inadvertently dropping compiler options determined by configure (things like -fwrapv) which can result in a broken interpreter.  I've changed the installer build to no longer do that.  But that does mean that users of the OS X installer will now see those missing compiler options during extension module builds and it is conceivable that could cause problems for some ext modules and there wouldn't be a simple way to work around them (e.g. by setting an OPT env value).  If no one has any strong objections, I'll plan to commit that patch soon.