Check recent nicks against nick list when tab completing

Nicks weren't checked against the nick list when tab completing, causing nicks that have PARTed to be completed when using bouncer playback from which PARTs are absent.

Untested because no Haiku build environment set up at the moment.

src/ChannelAgent.cpp

@@ -366,7 +366,8 @@ void ChannelAgent::TabExpansion()
 			// list in the correct order
 			for (i = 0; i < count; i++) {
 				BString* name(new BString(*fRecentNicks.ItemAt(i)));
-				if (!(name->ICompare(fLastExpansion.String(), strlen(fLastExpansion.String())))) {
+				if (!(name->ICompare(fLastExpansion.String(), strlen(fLastExpansion.String()))) &&
+					FindPosition(name.String()) > 0) {
 					// parse through list and nuke duplicate if present
 					for (int32 j = fCompletionNicks.CountItems() - 1; j >= 0; j--) {
 						if (!(name->ICompare(*fCompletionNicks.ItemAt(j)))) {