QGIS 2.18 Scale not being set up correctly

I’m working on adding scale based visibility on different layer. I’m currently using :

canvas.setDestinationCrs(crs)    
crs.createFromUserInput(name)    
crs = QgsCoordinateReferenceSystem()

to set the CRS of my project. However, when launching it with QGIS 2.18, it won’t load until I go to the project’s settings and click OK in the CRS panel. This problem does not apply to QGIS 3

Below is a GIF showing how to solve it using the GUI: