preload_replace and whitespace

I just discovered that the “preload_replace” tag does not work if spaces are included around the equal sign. Try it yourself:

{preload_replace:toast = 'is burnt'}
{preload_replace:bread='is buttered'}

The toast {toast}.

The bread {bread}.

You’ll find that the toast is not burnt, but the bread gets buttered.

At least in EE version 2.4.0.