Substitute with fold=true does not preserve rationals

[hersle]

It is annoying that

@variables x
substitute(1//2 * cos(x), x => 0)

gives 0.5 and not 1//2.

The reason is natural: cos(0) evaluates to 1.0 (not 1), giving (1//2) * 1.0, which is converted to 0.5.
Is there a way to fix this?

[ChrisRackauckas]

@shashi is this intended?