This patch has been merged upstream. Drop next update.
Commit: c8b1ea28364ef185ef61d2ca20230e92bb475b89

Index: src/XDGData/CMakeLists.txt
--- src/XDGData/CMakeLists.txt.orig
+++ src/XDGData/CMakeLists.txt
@@ -34,7 +34,20 @@ install(
     DESTINATION ${CMAKE_INSTALL_DATAROOTDIR}/mime/packages
 )
 
+configure_file(
+    FreeCAD.thumbnailer.in
+    ${CMAKE_BINARY_DIR}/FreeCAD.thumbnailer
+)
 install(
-    FILES FreeCAD.thumbnailer
+    FILES ${CMAKE_BINARY_DIR}/FreeCAD.thumbnailer
     DESTINATION ${CMAKE_INSTALL_DATAROOTDIR}/thumbnailers
+)
+
+configure_file(
+    ${CMAKE_SOURCE_DIR}/src/Tools/freecad-thumbnailer.in
+    ${CMAKE_BINARY_DIR}/freecad-thumbnailer
+)
+install(
+    PROGRAMS ${CMAKE_BINARY_DIR}/freecad-thumbnailer
+    TYPE BIN
 )
