Eeschema: IsCorner check for layer match

SCH_LINE can represent a bus, wire or graphic line.  Checking
for the corner needs to distinguish between these types.

Fixes: lp:1635984
* https://bugs.launchpad.net/kicad/+bug/1635984

eeschema/sch_collectors.cpp

@@ -263,7 +263,7 @@ bool SCH_COLLECTOR::IsCorner() const
     bool is_busentry1 = (dynamic_cast<SCH_BUS_ENTRY_BASE*>( m_List[1] ) != NULL);
 
     if( (m_List[0]->Type() == SCH_LINE_T) && (m_List[1]->Type() == SCH_LINE_T) )
-        return true;
+        return ( ( SCH_LINE* ) m_List[0])->GetLayer() == ( ( SCH_LINE* ) m_List[1])->GetLayer();
 
     if( (m_List[0]->Type() == SCH_LINE_T) && is_busentry1 )
         return true;