Show in amending commit list only the first parents

Signed-off-by: Nigel Westbury <nigelipse@miegel.org>

packages/git/src/browser/git-scm-provider.ts

@@ -401,6 +401,7 @@ export class GitAmendSupport implements ScmAmendSupport {
             this.repository,
             {
                 range: { toRevision: amendingHeadCommitSha, fromRevision: latestCommitSha },
+                firstParent: true,
                 maxCount: 50
             }
         );

packages/git/src/common/git.ts

@@ -547,6 +547,10 @@ export namespace Git {
              */
             readonly shortSha?: boolean;
 
+            /**
+             * Return only commits reached by following the first parent, giving a linear list of commits.
+             */
+            readonly firstParent?: boolean;
         }
 
         /**

packages/git/src/node/dugite-git.ts

@@ -643,6 +643,9 @@ export class DugiteGit implements Git {
         if (options && options.branch) {
             args.push(options.branch);
         }
+        if (options && options.firstParent) {
+            args.push('--first-parent');
+        }
         const range = this.mapRange((options || {}).range);
         args.push(...[range, '-C', '-M', '-m']);
         const maxCount = options && options.maxCount ? options.maxCount : 0;