Import the AngryBots package from the Asset Store in Unity 5.1 b4. Choose to let the ScriptUpdater run. It will fail with many errors like:
""Could not fetch error messages from compilerInvalidOperationException: The process must exit before getting the requested information.
System.Diagnostics.Process.get_ExitCode ()
(wrapper remoting-invoke-with-check) System.Diagnostics.Process:get_ExitCode ()
UnityEditor.Utils.Program.get_ExitCode () (at C:/buildslave/unity/build/Editor/Mono/Utils/Program.cs:104)
UnityEditor.Scripting.Compilers.ScriptCompilerBase.CompilationHadFailure () (at C:/buildslave/unity/build/Editor/Mono/Scripting/Compilers/ScriptCompilerBase.cs:105)
UnityEditor.Scripting.Compilers.ScriptCompilerBase.DumpStreamOutputToLog () (at C:/buildslave/unity/build/Editor/Mono/Scripting/Compilers/ScriptCompilerBase.cs:116)
UnityEditor.Scripting.Compilers.ScriptCompilerBase.GetCompilerMessages () (at C:/buildslave/unity/build/Editor/Mono/Scripting/Compilers/ScriptCompilerBase.cs:98)
"

and

"BCE0048: Type 'UnityEngine.Component' does not support slicing.
[Script Updater] Failed to resolve 'self.audio.clip' expression. This may cause expected updates to not be applied."

Regression from Unity 5.1 b1 (where it works without errors)