-e: Trying to build a webgl with a custom template fails with an error

-repro
--Create a "WebGLTemplates" directory in Assets
--Copy a template from playbackengines
--Adjust template as needed
--build webgl
--NOTICE error:

Filename: "C:\Program Files\Unity\Unity 5\Editor\Data\PlaybackEngines\webglsupport/BuildTools/Emscripten_Win/python/2.7.5.3_64bit/python.exe"
Arguments: "C:\Program Files\Unity\Unity 5\Editor\Data\PlaybackEngines\webglsupport/BuildTools/Emscripten/tools/file_packager.py" "WebGL.data" --no-heap-copy --js-output="fileloader.js" --preload "mainData" "methods_pointedto_by_uievents.xml" "resources.assets" "sharedassets0.assets" "Resources/unity_default_resources" "Resources/unity_builtin_extra"
index: -1
Exception: Invalid WebGL template path: C:\Program Files\Unity\Unity 5\Editor\Data\PlaybackEngines\webglsupport/BuildTools\WebGLTemplates\oss! Select a template in player settings.
at UnityEditor.WebGL.WebGlBuildPostprocessor.GetTemplateFolder () [0x00000] in <filename unknown>:0
at UnityEditor.WebGL.WebGlBuildPostprocessor.PostProcess (BuildPostProcessArgs args) [0x00000] in <filename unknown>:0
at UnityEditor.PostprocessBuildPlayer.Postprocess (BuildTarget target, System.String installPath, System.String companyName, System.String productName, Int32 width, Int32 height, System.String downloadWebplayerUrl, System.String manualDownloadWebplayerUrl, BuildOptions options, UnityEditor.RuntimeClassRegistry usedClassRegistry) [0x000c5] in C:\buildslave\unity\build\Editor\Mono\BuildPipeline\PostprocessBuildPlayer.cs:316
UnityEditor.BuildPipeline:BuildPlayerInternalNoCheck(String[], String, BuildTarget, BuildOptions, Boolean, UInt32