Issue #15316: Let exceptions raised during imports triggered by the fromlist of __import__ propagate. The problem previously was that if something listed in fromlist didn't exist then that's okay. The fix for that was too broad in terms of catching ImportError. The trick with the solution to this issue is that the proper refactoring of import thanks to importlib doesn't allow for a way to distinguish (portably) between an ImportError because finders couldn't find a loader, or a loader raised the exception. In Python 3.4 the hope is to introduce a new exception (e.g. ModuleNotFound) to make it clean to differentiate why ImportError was raised.

/* Cross platform case insensitive string compare functions
 */

#include "Python.h"

int
PyOS_mystrnicmp(const char *s1, const char *s2, Py_ssize_t size)
{
    if (size == 0)
        return 0;
    while ((--size > 0) &&
           (tolower((unsigned)*s1) == tolower((unsigned)*s2))) {
        if (!*s1++ || !*s2++)
            break;
    }
    return tolower((unsigned)*s1) - tolower((unsigned)*s2);
}

int
PyOS_mystricmp(const char *s1, const char *s2)
{
    while (*s1 && (tolower((unsigned)*s1++) == tolower((unsigned)*s2++))) {
        ;
    }
    return (tolower((unsigned)*s1) - tolower((unsigned)*s2));
}