QgsOgrFeatureIterator(): remove (hopefully!) useless code in subset s…

…tring case

Those lines where introduced per commit 5a9067e, but it is likely
that a following commit (391ec8a
potentially) make that useless.

I've added an extra test in addition to the one of 80e19b6
to test the case where the FID column is not selected

src/core/providers/ogr/qgsogrfeatureiterator.cpp

@@ -110,10 +110,6 @@ QgsOgrFeatureIterator::QgsOgrFeatureIterator( QgsOgrFeatureSource *source, bool
       mOgrLayer = QgsOgrProviderUtils::setSubsetString( mOgrLayer, mConn->ds, mSource->mEncoding, mSource->mSubsetString );
       // If the mSubsetString was a full SELECT ...., then mOgrLayer will be a OGR SQL layer != mOgrLayerOri
 
-      mFieldsWithoutFid.clear();
-      for ( int i = ( mFirstFieldIsFid ) ? 1 : 0; i < mSource->mFields.size(); i++ )
-        mFieldsWithoutFid.append( mSource->mFields.at( i ) );
-
       if ( !mOgrLayer )
       {
         close();

tests/src/python/test_provider_ogr_gpkg.py

@@ -547,6 +547,16 @@ def testSelectSubsetString(self):
         got = [feat for feat in vl.getFeatures(QgsFeatureRequest(1))]
         self.assertEqual(len(got), 1)  # this is the current behavior, broken
 
+        # Test setSubsetString() with a SELECT ... statement not selecting
+        # the FID column
+        vl = QgsVectorLayer(f'{tmpfile}', 'test', 'ogr')
+        vl.setSubsetString("SELECT name FROM test_layer WHERE name = 'two'")
+        got = [feat for feat in vl.getFeatures()]
+        self.assertEqual(len(got), 1)
+
+        attributes = got[0].attributes()
+        self.assertEqual(attributes[0], 'two')
+
     def testEditSubsetString(self):
 
         tmpfile = os.path.join(self.basetestpath, 'testEditSubsetString.gpkg')