From 818660d1a766c829a455042e751b38ca93b1005e Mon Sep 17 00:00:00 2001
From: Kirill Likhodedov <Kirill.Likhodedov@gmail.com>
Date: Sun, 23 Jun 2019 23:15:20 +0100
Subject: [PATCH] git: remember the previous HEAD position before pull/merge

The revision is used to calculate updated files. It used to work, because Repository.getCurrentRevision returns the cached version which is not updated unless explicitly requested and unless a VFS refresh is received indicating that the HEAD file has changed: the first didn't happen, the latter most likely didn't happen as well, but it is just by luck.

GitOrigin-RevId: a44a65db4167dc15a459b481702f62cb0c187519
---
 .../src/git4idea/actions/GitMergeAction.java        | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/plugins/git4idea/src/git4idea/actions/GitMergeAction.java b/plugins/git4idea/src/git4idea/actions/GitMergeAction.java
index c1594f1436e1..cbb2ec8ff703 100644
--- a/plugins/git4idea/src/git4idea/actions/GitMergeAction.java
+++ b/plugins/git4idea/src/git4idea/actions/GitMergeAction.java
@@ -115,6 +115,8 @@ abstract class GitMergeAction extends GitRepositoryAction {
           }
         }
 
+        String beforeRevision = repository.getCurrentRevision();
+
         try (AccessToken ignore = DvcsUtil.workingTreeChangeStarted(project, getActionName())) {
           GitCommandResult result = git.runCommand(() -> {
             GitLineHandler handler = handlerProvider.compute();
@@ -124,14 +126,11 @@ abstract class GitMergeAction extends GitRepositoryAction {
             return handler;
           });
 
-          String revision = repository.getCurrentRevision();
-          if (revision == null) {
-            return;
+          if (beforeRevision != null) {
+            GitRevisionNumber currentRev = new GitRevisionNumber(beforeRevision);
+            handleResult(result, project, mergeConflict, localChangesDetector, untrackedFilesDetector, repository, currentRev, beforeLabel,
+                         updatedRanges);
           }
-
-          GitRevisionNumber currentRev = new GitRevisionNumber(revision);
-          handleResult(result, project, mergeConflict, localChangesDetector, untrackedFilesDetector, repository, currentRev, beforeLabel,
-                       updatedRanges);
         }
       }
     }.queue();