(GH-1689) Delete packaging scripts before upgrade

It is possible, due to the way that Package Reducer works, that there
are extra files left in the package directory when doing an upgrade
of a package.  This can cause a package upgrade to fail.  Prior to
performing the upgrade, delete all packaging scripts (chocolateyInstall,
chocolateyUninstall, and chocolateyBeforeModify) from the package
folder, these will then be replaced during the upgrade, if they are
still required..

src/chocolatey/infrastructure.app/services/NugetService.cs

@@ -1146,6 +1146,8 @@ public virtual void backup_existing_version(ChocolateyConfiguration config, IPac
                     try
                     {
                         _fileSystem.copy_directory(backupLocation, pkgInstallPath, overwriteExisting: true);
+
+                        remove_packaging_files_prior_to_upgrade(pkgInstallPath, config.CommandName);
                     }
                     catch (Exception ex)
                     {
@@ -1167,6 +1169,29 @@ process locking the folder or files. Please make sure nothing is
             }
         }
 
+        public virtual void remove_packaging_files_prior_to_upgrade(string directoryPath, string commandName)
+        {
+            if (commandName.to_lower() == "upgrade")
+            {
+                // Due to the way that Package Reducer works, there is a potential that a Chocolatey Packaging
+                // script could be incorrectly left in place during an upgrade operation.  To guard against this,
+                // remove any Chocolatey Packaging scripts, which will then be restored by the new package, if
+                // they are still required
+                var filesToDelete = new List<string> {"chocolateyinstall", "chocolateyuninstall", "chocolateybeforemodify"};
+                var packagingScripts = _fileSystem.get_files(directoryPath, "*.ps1", SearchOption.AllDirectories)
+                    .Where(p => filesToDelete.Contains(_fileSystem.get_file_name_without_extension(p).to_lower()));
+
+                foreach (var packagingScript in packagingScripts)
+                {
+                    if (_fileSystem.file_exists(packagingScript))
+                    {
+                        this.Log().Debug("Deleting file {0}".format_with(packagingScript));
+                        _fileSystem.delete_file(packagingScript);
+                    }
+                }
+            }
+        }
+
         public virtual void backup_changed_files(string packageInstallPath, ChocolateyConfiguration config, ChocolateyPackageInformation packageInfo)
         {
             if (packageInfo == null || packageInfo.Package == null) return;