Comment 16 for bug 1674273

I think you are not hitting any bug at all ?
According to the man, ndots has nothing to do with adding or not adding search list to the query, it only determines if you need to try absolute request first OR with search list first. The first non-error result is returned to the client.

resolv.conf / ndots man page : sets a threshold for the number of dots which must appear in a name given to res_query(3) (see resolver(3)) before an initial absolute query will be made. The default for n is 1, meaning that if there are any dots in a name, the name will be *tried first* as an absolute name *before any search list elements are appended* to it. The value for this option is silently capped to 15.

Your logs with ndots:1 with a name having >ndots are following the man :
- first query is done for absolute name some.long.non-existent.name : NXDOMAIN. resolving is not done, need to continue.
- adding search list, a match is found and returned

As far as I can tell, xenial resolving is not broken, but yakkety is. That's another story.