2 files changed, 31 insertions, 6 deletions
diff --git a/pkg/vcs/git.go b/pkg/vcs/git.go
index f1311e312..efcb64470 100644
--- a/pkg/vcs/git.go
+++ b/pkg/vcs/git.go
@@ -805,6 +805,10 @@ func (git Git) BaseForDiff(diff []byte, tracer debugtracer.DebugTracer) ([]*Base
 		if _, ignore := ignoreFiles[file.Name]; ignore {
 			continue
 		}
+		if _, ok := nameToHash[file.Name]; ok {
+			// We only care about the first occurrence of a file in the diff series.
+			continue
+		}
 		if ok, err := git.verifyHash(file.LeftHash); err != nil {
 			return nil, fmt.Errorf("hash verification failed: %w", err)
 		} else if !ok {
@@ -812,12 +816,8 @@ func (git Git) BaseForDiff(diff []byte, tracer debugtracer.DebugTracer) ([]*Base
 			tracer.Logf("unknown object %s, stopping base commit search", file.LeftHash)
 			return nil, nil
 		}
-		if _, ok := nameToHash[file.Name]; !ok {
-			// If the diff is actually a concatenation of several diffs, we only
-			// want to remember the first left side hash for each file.
-			fileNames = append(fileNames, file.Name)
-			nameToHash[file.Name] = file.LeftHash
-		}
+		fileNames = append(fileNames, file.Name)
+		nameToHash[file.Name] = file.LeftHash
 		args = append(args, "--find-object="+file.LeftHash)
 	}
 	tracer.Logf("extracted %d left blob hashes", len(nameToHash))
diff --git a/pkg/vcs/git_test.go b/pkg/vcs/git_test.go
index f2fd9e059..d867ed692 100644
--- a/pkg/vcs/git_test.go
+++ b/pkg/vcs/git_test.go
@@ -599,6 +599,31 @@ index fa49b07..01c887f 100644
 		require.NoError(t, err)
 		require.Nil(t, base)
 	})
+	t.Run("multiple modifications", func(t *testing.T) {
+		map1, _ := repo.repo.fileHashes(commit3.Hash, []string{"a.txt"})
+
+		twoDiffs := []byte(fmt.Sprintf(`diff --git a/a.txt b/a.txt
+index %s..1111111 100644
+--- a/a.txt
++++ b/a.txt
+@@ -1 +1 @@
+-update a.txt
++update a.txt again
+diff --git a/a.txt b/a.txt
+index 1111111..2222222 100644
+--- a/a.txt
++++ b/a.txt
+@@ -1 +1 @@
+-update a.txt again
++update a.txt again and again
+`, map1["a.txt"]))
+
+		base, err := repo.repo.BaseForDiff(twoDiffs, &debugtracer.TestTracer{T: t})
+		require.NoError(t, err)
+		require.Len(t, base, 1)
+
+		assert.Equal(t, commit3.Hash, base[0].Hash)
+	})
 }
 
 func TestBaseForDiffMerge(t *testing.T) {