Merge branch 'jk/ident-ai-canonname-could-be-null' into maint

In the codepath that comes up with the hostname to be used in an
e-mail when the user didn't tell us, we looked at ai_canonname
field in struct addrinfo without making sure it is not NULL first.

* jk/ident-ai-canonname-could-be-null:
  ident: handle NULL ai_canonname

Author: gitster

ident.c

@@ -101,7 +101,7 @@ static int canonical_name(const char *host, struct strbuf *out)
 	memset (&hints, '\0', sizeof (hints));
 	hints.ai_flags = AI_CANONNAME;
 	if (!getaddrinfo(host, NULL, &hints, &ai)) {
-		if (ai && strchr(ai->ai_canonname, '.')) {
+		if (ai && ai->ai_canonname && strchr(ai->ai_canonname, '.')) {
 			strbuf_addstr(out, ai->ai_canonname);
 			status = 0;
 		}