Fixes #451 - Stops apply changes from HEAD if the sha is missing or HEAD

Also allows for vscode undo support for the applied changes

CHANGELOG.md

@@ -4,6 +4,10 @@ All notable changes to this project will be documented in this file.
 
 The format is based on [Keep a Changelog](http://keepachangelog.com/) and this project adheres to [Semantic Versioning](http://semver.org/).
 
+## [Unreleased]
+### Fixed
+- Fixes [#451](https://github.com/eamodio/vscode-gitlens/issues/451) - "apply Changes" has discarded all my changes.
+
 ## [8.5.1] - 2018-07-18
 ### Added
 - Adds emoji support, e.g. :smile: in commit messages will now be 😃 — closes [#429](https://github.com/eamodio/vscode-gitlens/issues/429)

src/views/explorerCommands.ts

@@ -100,8 +100,11 @@ export class ExplorerCommands extends Disposable {
     }
 
     private async applyChanges(node: CommitFileNode | StashFileNode | StatusFileNode) {
-        await Container.git.checkoutFile(node.uri);
-        return this.openFile(node);
+        await this.openFile(node);
+
+        if (node.uri.sha !== undefined && node.uri.sha !== 'HEAD') {
+            await Container.git.checkoutFile(node.uri);
+        }
     }
 
     private closeRepository(node: RepositoryNode | StatusNode) {