allow dispatch on axes type in sizes_to_blocks

Author: dlfivefifty

src/blockarray.jl

@@ -233,7 +233,9 @@ mortar(blocks::AbstractArray{R, N}, block_sizes::Vararg{AbstractVector{Int}, N})
 
 mortar(blocks::AbstractArray) = mortar(blocks, sizes_from_blocks(blocks))
 
-function sizes_from_blocks(blocks::AbstractArray{<:Any, N}) where N
+sizes_from_blocks(blocks) = sizes_from_blocks(blocks, axes(blocks)) # allow overriding on axes
+
+function sizes_from_blocks(blocks::AbstractArray{<:Any, N}, _) where N
     if length(blocks) == 0
         return zeros.(Int, size(blocks))
     end