Expose Subversion revision number (calculated via "svnversion .") to Python. Add C API function Py_GetBuildNumber(), add it to the interactive prompt banner (i.e. Py_GetBuildInfo()), and add it as the sys.build_number attribute. The build number is a string instead of an int because it may contain a trailing 'M' if there are local modifications.

#include "Python.h"

#ifndef PLATFORM
#define PLATFORM "unknown"
#endif

const char *
Py_GetPlatform(void)
{
	return PLATFORM;
}