Set errno to 0 before sscanf, as sscanf doesn't set it to 0 if there were no error

src/lib/cpt-read.c

@@ -143,6 +143,7 @@ static int cpt_parse_comment(const char *line, cpt_t *cpt)
 {
   char name[32], arg[32];
 
+  errno = 0;
   switch (sscanf(line, " %31s = %31s ", name, arg))
     {
     case 0: