From 1de7b42588aa530f926cb64f78b12fbe06f39bbf Mon Sep 17 00:00:00 2001
From: Nyall Dawson <nyall.dawson@gmail.com>
Date: Tue, 26 Sep 2017 06:30:08 +1000
Subject: [PATCH] Ensure multilinestring dimensionality is respected when
 adding new lines

---
 src/core/geometry/qgsmultilinestring.cpp | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/src/core/geometry/qgsmultilinestring.cpp b/src/core/geometry/qgsmultilinestring.cpp
index b0bc11aa440..009bbe173be 100644
--- a/src/core/geometry/qgsmultilinestring.cpp
+++ b/src/core/geometry/qgsmultilinestring.cpp
@@ -116,7 +116,18 @@ bool QgsMultiLineString::addGeometry( QgsAbstractGeometry *g )
     return false;
   }
 
-  setZMTypeFromSubGeometry( g, QgsWkbTypes::MultiLineString );
+  if ( mGeometries.empty() )
+  {
+    setZMTypeFromSubGeometry( g, QgsWkbTypes::MultiLineString );
+  }
+  if ( is3D() && !g->is3D() )
+    g->addZValue();
+  else if ( !is3D() && g->is3D() )
+    g->dropZValue();
+  if ( isMeasure() && !g->isMeasure() )
+    g->addMValue();
+  else if ( !isMeasure() && g->isMeasure() )
+    g->dropMValue();
   return QgsGeometryCollection::addGeometry( g );
 }