Usually we want no difference between the upstream project that we fork
via git-subtree, and our copy. However, for the subprojects, we need to
patch them. Do it.
If you know a better way, that allows to overwriting the subprojects
please send a patch.
N_ACD_E_DROPPED is an error code of n-acd, albeit internal. But such codes are returned
as postive values, unlike error codes from errno.h (which are negative).
Fix comparing for N_ACD_E_DROPPED, otherwise the error gets propagate to the caller
when we should handle it internally.
