fix scale warnings for layouts

src/args.jl

@@ -1644,7 +1644,7 @@ function warn_on_unsupported_scales(pkg::AbstractBackend, plotattributes::AKW)
     for k in (:xscale, :yscale, :zscale, :scale)
         if haskey(plotattributes, k)
             v = plotattributes[k]
-            if !is_scale_supported(pkg, v)
+            if !all(x->is_scale_supported(pkg, x), v)
                 @warn(
                     "scale $v is unsupported with $pkg.  Choose from: $(supported_scales(pkg))"
                 )

test/runtests.jl

@@ -40,6 +40,7 @@ end
 include("test_defaults.jl")
 include("test_pipeline.jl")
 include("test_axes.jl")
+include("test_layouts.jl")
 include("test_contours.jl")
 include("test_axis_letter.jl")
 include("test_components.jl")

test/test_layouts.jl

@@ -0,0 +1,9 @@
+using Plots, Test
+
+@testset "Subplot sclicing" begin
+    pl = @test_nowarn plot(rand(4,8), layout=4, yscale=[:identity :identity :log10 :log10])
+    @test pl[1][:yaxis][:scale] == :identity
+    @test pl[2][:yaxis][:scale] == :identity
+    @test pl[3][:yaxis][:scale] == :log10
+    @test pl[4][:yaxis][:scale] == :log10
+end