[librsvg/librsvg-2.50] push_coord_units: Always push a Viewport, instead of sometimes returning a copy of the last one

[Federico Mena Quintero <federico src gnome org>]

commit b700ad1941238044ea411a29732cd3ea46492be9
Author: Federico Mena Quintero <federico gnome org>
Date:   Mon Sep 28 16:19:01 2020 -0500

    push_coord_units: Always push a Viewport, instead of sometimes returning a copy of the last one

 rsvg_internals/src/drawing_ctx.rs | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)
---
diff --git a/rsvg_internals/src/drawing_ctx.rs b/rsvg_internals/src/drawing_ctx.rs
index 7f78aaf2..b7ded244 100644
--- a/rsvg_internals/src/drawing_ctx.rs
+++ b/rsvg_internals/src/drawing_ctx.rs
@@ -308,10 +308,14 @@ impl DrawingCtx {
     }
 
     pub fn push_coord_units(&self, units: CoordUnits) -> ViewParams {
-        if units == CoordUnits::ObjectBoundingBox {
-            self.push_view_box(1.0, 1.0)
-        } else {
-            self.get_view_params()
+        match units {
+            CoordUnits::ObjectBoundingBox => self.push_view_box(1.0, 1.0),
+
+            CoordUnits::UserSpaceOnUse => {
+                // Duplicate the topmost viewport;
+                let viewport = self.get_top_viewport();
+                self.push_viewport(viewport)
+            }
         }
     }