Fixes #806 - use merge base with .. compares

CHANGELOG.md

@@ -8,6 +8,7 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/) and this p
 
 ### Fixed
 
+- Fixes [#806](https://github.com/eamodio/vscode-gitlens/issues/806) - file diff in two-dot branch compare should only show the changes in one branch
 - Fixes [#756](https://github.com/eamodio/vscode-gitlens/issues/756) - Merge commit shows only the changes from the last commit on those files
 - Fixes [#809](https://github.com/eamodio/vscode-gitlens/issues/809) - Wrong commit diff in file history
 - Fixes [#685](https://github.com/eamodio/vscode-gitlens/issues/685) - GitLens not loading for a single repository

src/views/nodes/compareBranchNode.ts

@@ -36,10 +36,15 @@ export class CompareBranchNode extends ViewNode {
         return `gitlens:repository(${this.branch.repoPath}):compare:branch(${this.branch.name}):compareWith`;
     }
 
-    getChildren(): ViewNode[] {
+    async getChildren(): Promise<ViewNode[]> {
         if (this._compareWith === undefined) return [];
 
         if (this._children === undefined) {
+            let ref1 = (this._compareWith && this._compareWith.ref) || 'HEAD';
+            if (this.comparisonNotation === '..') {
+                ref1 = (await Container.git.getMergeBase(this.branch.repoPath, ref1, this.branch.ref)) || ref1;
+            }
+
             this._children = [
                 new ResultsCommitsNode(
                     this.view,
@@ -56,7 +61,7 @@ export class CompareBranchNode extends ViewNode {
                     this.view,
                     this,
                     this.uri.repoPath!,
-                    (this._compareWith && this._compareWith.ref) || ">'HEAD',
+                    ref1,
                     this.compareWithWorkingTree ? '' : this.branch.ref,
                     this.getFilesQuery.bind(this)
                 )

src/views/nodes/compareResultsNode.ts

@@ -49,8 +49,13 @@ export class CompareResultsNode extends SubscribeableViewNode {
         return this._ref2;
     }
 
-    getChildren(): ViewNode[] {
+    async getChildren(): Promise<ViewNode[]> {
         if (this._children === undefined) {
+            let ref1 = this._ref1.ref;
+            if (this.comparisonNotation === '..') {
+                ref1 = (await Container.git.getMergeBase(this.repoPath, ref1, this._ref2.ref)) || ref1;
+            }
+
             this._children = [
                 new ResultsCommitsNode(
                     this.view,
@@ -67,7 +72,7 @@ export class CompareResultsNode extends SubscribeableViewNode {
                     this.view,
                     this,
                     this.uri.repoPath!,
-                    this._ref1.ref,
+                    ref1,
                     this._ref2.ref,
                     this.getFilesQuery.bind(this)
                 )