From file util_str.c in function strupper_m: 

 while (*s && !(((unsigned char)s[0]) & 0x7f)) {

The expression !(((unsigned char)s[0]) & 0x7f) is FALSE for all values of s[0]
except 0 and 0x80. The desired optimization never takes place. Should be
corrected to:

 while (*s && !(((unsigned char)s[0]) & 0x80)) {

Same for strlower_m.