propagate NaN value in median

Author: aplavin

src/Statistics.jl

@@ -814,7 +814,8 @@ Like [`median`](@ref), but may overwrite the input vector.
 function median!(v::AbstractVector)
     isempty(v) && throw(ArgumentError("median of an empty array is undefined, $(repr(v))"))
     eltype(v)>:Missing && any(ismissing, v) && return missing
-    any(x -> x isa Number && isnan(x), v) && return convert(eltype(v), NaN)
+    nanix = findfirst(x -> x isa Number && isnan(x), v)
+    isnothing(nanix) || return v[nanix]
     inds = axes(v, 1)
     n = length(inds)
     mid = div(first(inds)+last(inds),2)