printing expressions with Foo{<:Bar} syntax

[visr]

#20414 introduced syntactic sugar to make Ref{<:Real} shorthand for Ref{T} where T<:Real.
Now I'm trying to print some expressions making use of this syntax, but I end up with invalid code.
In short, AST printing rule 1, parse(string(ex)) == ex, seems to be violated:

Fine for full syntax:

julia> eval(parse(string(:(Ref{T} where T<:Real))))
Ref{T} where T<:Real

It goes wrong for the shorthand:

julia> eval(parse(string(:(Ref{<:Real}))))
ERROR: unsupported or misplaced expression $
Stacktrace:
 [1] eval(::Module, ::Any) at .\boot.jl:291
 [2] eval(::Any) at .\boot.jl:290

The intermediate values look like this:

julia> Ref{<:Real}
Ref{#s1} where #s1<:Real

julia> :(Ref{<:Real})
:(Ref{$(Expr(:<:, :Real))})

julia> string(:(Ref{<:Real}))
"Ref{\$(Expr(:<:, :Real))}"

julia> parse(string(:(Ref{<:Real})))
:(Ref{$(Expr(:$, :(Expr(:<:, :Real))))})

Seen on v0.6.0 and master.