Hugo 0.27.1: One bugfix

This fixes a regression introduced in Go 1.9 which lead to HTML in shortcodes in multi output Hugo sites being wrongly escaped in some cases.

• Fix escaped HTML Go 1.9 multioutput issue (#3880) 2d613dd9 @bep #3876

• Bump to Go 1.9 in the Snap build 642ba6ca @bep