layer definition: always use relative paths regardless whether or not…

… the file already exists (fixes #14340)

src/app/qgisapp.cpp

@@ -5650,7 +5650,6 @@ void QgisApp::saveAsFile()
 
 void QgisApp::saveAsLayerDefinition()
 {
-
   QString path = QFileDialog::getSaveFileName( this, "Save as Layer Definition File", QDir::home().path(), "*.qlr" );
   QgsDebugMsg( path );
   if ( path.isEmpty() )

src/core/qgslayerdefinition.cpp

@@ -151,22 +151,22 @@ bool QgsLayerDefinition::exportLayerDefinition( QString path, const QList<QgsLay
     path = path.append( ".qlr" );
 
   QFile file( path );
-  QFileInfo fileinfo( file );
 
-  QDomDocument doc( "qgis-layer-definition" );
-  if ( !exportLayerDefinition( doc, selectedTreeNodes, errorMessage, fileinfo.canonicalFilePath() ) )
-    return false;
-  if ( file.open( QFile::WriteOnly | QFile::Truncate ) )
-  {
-    QTextStream qlayerstream( &file );
-    doc.save( qlayerstream, 2 );
-    return true;
-  }
-  else
+  if ( !file.open( QFile::WriteOnly | QFile::Truncate ) )
   {
     errorMessage = file.errorString();
     return false;
   }
+
+  QFileInfo fileinfo( file );
+
+  QDomDocument doc( "qgis-layer-definition" );
+  if ( !exportLayerDefinition( doc, selectedTreeNodes, errorMessage, fileinfo.canonicalFilePath() ) )
+    return false;
+
+  QTextStream qlayerstream( &file );
+  doc.save( qlayerstream, 2 );
+  return true;
 }
 
 bool QgsLayerDefinition::exportLayerDefinition( QDomDocument doc, const QList<QgsLayerTreeNode*>& selectedTreeNodes, QString &errorMessage, const QString& relativeBasePath )