1 files changed, 38 insertions, 27 deletions

diff --git a/plumbing/object/commit_walker_file.go b/plumbing/object/commit_walker_file.go
index 1af9ec1..6f16e61 100644
--- a/plumbing/object/commit_walker_file.go
+++ b/plumbing/object/commit_walker_file.go
@@ -3,6 +3,8 @@ package object
 import (
 	"io"
 
+	"gopkg.in/src-d/go-git.v4/plumbing"
+
 	"gopkg.in/src-d/go-git.v4/plumbing/storer"
 )
 
@@ -10,17 +12,19 @@ type commitFileIter struct {
 	fileName      string
 	sourceIter    CommitIter
 	currentCommit *Commit
-	all           bool
+	checkParent   bool
 }
 
 // NewCommitFileIterFromIter returns a commit iterator which performs diffTree between
 // successive trees returned from the commit iterator from the argument. The purpose of this is
 // to find the commits that explain how the files that match the path came to be.
-func NewCommitFileIterFromIter(fileName string, commitIter CommitIter, all bool) CommitIter {
+// If checkParent is true then the function double checks if potential parent (next commit in a path)
+// is one of the parents in the tree (it's used by `git log --all`).
+func NewCommitFileIterFromIter(fileName string, commitIter CommitIter, checkParent bool) CommitIter {
 	iterator := new(commitFileIter)
 	iterator.sourceIter = commitIter
 	iterator.fileName = fileName
-	iterator.all = all
+	iterator.checkParent = checkParent
 	return iterator
 }
 
@@ -74,36 +78,14 @@ func (c *commitFileIter) getNextFileCommit() (*Commit, error) {
 			return nil, diffErr
 		}
 
-		foundChangeForFile := false
-		for _, change := range changes {
-			if change.name() != c.fileName {
-				continue
-			}
-
-			// filename matches, now check if source iterator contains all commits (from all refs)
-			if c.all {
-				// for `git log --all` also check if the next commit comes from the same parent
-				for _, h := range c.currentCommit.ParentHashes {
-					if h == parentCommit.Hash {
-						foundChangeForFile = true
-						break
-					}
-				}
-			} else {
-				foundChangeForFile = true
-			}
-
-			if foundChangeForFile {
-				break
-			}
-		}
+		found := c.hasFileChange(changes, parentCommit)
 
 		// Storing the current-commit in-case a change is found, and
 		// Updating the current-commit for the next-iteration
 		prevCommit := c.currentCommit
 		c.currentCommit = parentCommit
 
-		if foundChangeForFile == true {
+		if found {
 			return prevCommit, nil
 		}
 
@@ -114,6 +96,35 @@ func (c *commitFileIter) getNextFileCommit() (*Commit, error) {
 	}
 }
 
+func (c *commitFileIter) hasFileChange(changes Changes, parent *Commit) bool {
+	for _, change := range changes {
+		if change.name() != c.fileName {
+			continue
+		}
+
+		// filename matches, now check if source iterator contains all commits (from all refs)
+		if c.checkParent {
+			if parent != nil && isParentHash(parent.Hash, c.currentCommit) {
+				return true
+			}
+			continue
+		}
+
+		return true
+	}
+
+	return false
+}
+
+func isParentHash(hash plumbing.Hash, commit *Commit) bool {
+	for _, h := range commit.ParentHashes {
+		if h == hash {
+			return true
+		}
+	}
+	return false
+}
+
 func (c *commitFileIter) ForEach(cb func(*Commit) error) error {
 	for {
 		commit, nextErr := c.Next()