New comment by rapenne-s on mblaze repository

https://github.com/leahneukirchen/mblaze/issues/257#issuecomment-1987267017

Comment:
I got a diff with which the tests pass, not sure it's good though

```
diff --git a/mmime.c b/mmime.c
index 6334569..b521efc 100644
--- a/mmime.c
+++ b/mmime.c
@@ -347,7 +347,7 @@ print_header(char *line) {
                if (!highbit) {
                        if (e-s >= 998)
                                goto force_qp;
-                       if (e-s >= 78 - linelen) {
+                       if (e-s >= 78 - linelen && linelen > 0) {
                                // wrap in advance before long word
                                printf("\n");
                                linelen = 0;
```