Merge pull request #1765 from pfitzseb/sp/juno2

honour `html_output_format` in Juno

src/output.jl

@@ -267,9 +267,21 @@ function showjuno(io::IO, m, plt)
     plt[:thickness_scaling] *= scale
 
     prepare_output(plt)
-    _show(io, m, plt)
+    try
+      _showjuno(io, m, plt)
+    finally
+      plt[:size] = sz
+      plt[:dpi] = dpi
+      plt[:thickness_scaling] = thickness_scaling
+    end
+end
 
-    plt[:size] = sz
-    plt[:dpi] = dpi
-    plt[:thickness_scaling] = thickness_scaling
+function _showjuno(io::IO, m::MIME"image/svg+xml", plt)
+  if Symbol(plt.attr[:html_output_format]) ≠ :svg
+    throw(MethodError(show, (typeof(m), typeof(plt))))
+  else
+    _show(io, m, plt)
+  end
 end
+
+_showjuno(io::IO, m, plt) = _show(io, m, plt)