Referencing pair of subequations as (1a,b) using cleveref

If I have subequations (1a) and (1b), then when I reference them using cref I would like them to be typeset as (1a,b), but by default they appear as (1a) and (1b). How do I change this?

MWE:

documentclass{article}

usepackage{amsmath}
usepackage[hidelinks]{hyperref}
usepackage[compress]{cleveref}
crefrangelabelformat{equation}{(#3#1#4--#5crefstripprefix{#1}#2#6)}

begin{document}

begin{subequations}
begin{align}
    a&=b    label{eqn:1a}
    c&=d    label{eqn:1b}
    e&=f    label{eqn:1c}
end{align}
end{subequations}

begin{equation}
    x=y     label{eqn:2}
end{equation}

Reference to the trio of equations works correctly as a range: `cref{eqn:1a,eqn:1b,eqn:1c}', 
but reference to a pair yields `cref{eqn:1a,eqn:1b}' when I want `eqs. (1a,b)'. In addition, 
I would like `cref{eqn:1a,eqn:1b,eqn:2}' to appear as 'eqs. (1a,b) and (2)'.
end{document}