[Dovecot] Possible bug in Maildir++ quota?

While researching a possible bug in our custom-made Maildir++ expiration script, I found the following in src/plugins/quota/quota-maildir.c.

| static const char * | maildir_list_next(struct maildir_list_context *ctx, time_t *mtime_r) | { | [...] | *mtime_r = st.st_size; | return str_c(ctx->path); | }

As far as I unterstand, this seems incorrect, because the value in mtime_r is used, for example, in maildirs_check_have_changed to check whether any maildirs or folders have changed.

If this isn't a bug, please satisfy my own curiosity and tell me what I'm missing.

Ulrich