(GH-1210) CacheLocation - Prevent nested chocolatey directories

This ensures that the CacheLocation only appends chocolatey to the TEMP variable
if it has not already been added. Otherwise multiple package installs in the
same process result in an ever deeper nested chocolatey cache folders, resulting
in eventual `PATH too long` errors. This appears to affect only API usage of
Chocolatey.

src/chocolatey/infrastructure.app/builders/ConfigurationBuilder.cs

@@ -195,7 +195,16 @@ private static void set_machine_sources(ChocolateyConfiguration config, ConfigFi
         private static void set_config_items(ChocolateyConfiguration config, ConfigFileSettings configFileSettings, IFileSystem fileSystem)
         {
             config.CacheLocation = Environment.ExpandEnvironmentVariables(set_config_item(ApplicationParameters.ConfigSettings.CacheLocation, configFileSettings, string.IsNullOrWhiteSpace(configFileSettings.CacheLocation) ? string.Empty : configFileSettings.CacheLocation, "Cache location if not TEMP folder."));
-            if (string.IsNullOrWhiteSpace(config.CacheLocation)) config.CacheLocation = fileSystem.combine_paths(fileSystem.get_temp_path(), "chocolatey"); // System.Environment.GetEnvironmentVariable("TEMP");
+            if (string.IsNullOrWhiteSpace(config.CacheLocation)) {
+                config.CacheLocation = fileSystem.get_temp_path(); // System.Environment.GetEnvironmentVariable("TEMP");
+                // TEMP gets set in EnvironmentSettings, so it may already have 
+                // chocolatey in the path when it installs the next package from
+                // the API. 
+                if(!config.CacheLocation.EndsWith("chocolatey")) {
+                    config.CacheLocation = fileSystem.combine_paths(fileSystem.get_temp_path(), "chocolatey");
+                }
+            }
+
             // if it is still empty, use temp in the Chocolatey install directory.
             if (string.IsNullOrWhiteSpace(config.CacheLocation)) config.CacheLocation = fileSystem.combine_paths(ApplicationParameters.InstallLocation, "temp");