(GH-1949) Release mode - account for null entry assembly

Some testing platforms will not provide an entry assembly, so it can
come back null. In this case, look for the entry assembly first, then
look at the executing assembly. This should work in near all test cases.
This is also not part of official release code.

src/chocolatey/infrastructure.app/ApplicationParameters.cs

@@ -45,8 +45,10 @@ public static class ApplicationParameters
         // we might be testing on a server or in the local debugger. Either way,
         // start from the assembly location and if unfound, head to the machine
         // locations instead. This is a merge of official and Debug modes.
-        public static readonly string InstallLocation = _fileSystem.file_exists(_fileSystem.combine_paths(_fileSystem.get_directory_name(Assembly.GetEntryAssembly().CodeBase.Replace("file:///", string.Empty)), "chocolatey.dll")) ?
-                _fileSystem.get_directory_name(Assembly.GetEntryAssembly().CodeBase.Replace("file:///", string.Empty)) :
+        private static IAssembly _assemblyForLocation = Assembly.GetEntryAssembly().UnderlyingType != null ? Assembly.GetEntryAssembly() : Assembly.GetExecutingAssembly();
+        public static readonly string InstallLocation = _fileSystem.file_exists(_fileSystem.combine_paths(_fileSystem.get_directory_name(_assemblyForLocation.CodeBase.Replace("file:///", string.Empty)), "chocolatey.dll")) ||
+                                                        _fileSystem.file_exists(_fileSystem.combine_paths(_fileSystem.get_directory_name(_assemblyForLocation.CodeBase.Replace("file:///", string.Empty)), "choco.exe")) ?
+                _fileSystem.get_directory_name(_assemblyForLocation.CodeBase.Replace("file:///", string.Empty)) :
                 !string.IsNullOrWhiteSpace(System.Environment.GetEnvironmentVariable(ChocolateyInstallEnvironmentVariableName)) ?
                     System.Environment.GetEnvironmentVariable(ChocolateyInstallEnvironmentVariableName) :
                     @"C:\ProgramData\Chocolatey"