git2go Patch() returns diff for first file only

I was trying to configure rb-gateway (simple proxy written in Go, which supports custom repositories for ReviewBoard).
git2go is built from next branch together with libgit2.
Problem occurs during generation patch from diff. Code below returns always first file changes only.

package main
import (
"github.com/libgit2/git2go"
"log"
)
func main() {
gitRepo, err := git.OpenRepository("repo_path")
if err != nil {
log.Fatal(err)
}
commitOid, err := git.NewOid("commit_id_sha1")
if err != nil {
log.Fatal(err)
}
commit, err := gitRepo.LookupCommit(commitOid)
if err != nil {
log.Fatal(err)
}
commitTree, err := commit.Tree()
if err != nil {
log.Fatal(err)
}
options, err := git.DefaultDiffOptions()
if err != nil {
log.Fatal(err)
}
// Specifying full patch indices.
options.IdAbbrev = 40
var parentTree *git.Tree
if commit.ParentCount() > 0 {
parentTree, err = commit.Parent(0).Tree()
if err != nil {
log.Fatal(err)
}
}
gitDiff, err := gitRepo.DiffTreeToTree(parentTree, commitTree, &options)
if err != nil {
log.Fatal(err)
}
patch, err := gitDiff.Patch(0)
if err != nil {
log.Fatal(err)
}
patchString, err := patch.String()
if err != nil {
log.Fatal(err)
}
log.Printf("%s", patchString)
patch.Free()
}

Environment:
go version go1.4.2 linux/amd64
git version 1.8.3.1
libgit2 and git2go latest
Linux 3.10.0-327.4.5.el7.x86_64 (CentOS)

You need to post all the necessary elements to reproduce your problem: How to create a Minimal, Complete, and Verifiable example. This includes input and expected output.

For example, in reproducible form, to show all file patch diffs in a commit:

patchdiffs.go:

package main
import (
"github.com/libgit2/git2go"
"log"
)
/*
github.com/libgit2/git2go
commit 80cf533fe4e48ddfab3015d9570f2833951c1dea
Author: David Pierce <david.pierce@moz.com>
Date:   Sat Sep 26 15:37:48 2015 -0700
Config#LookupString uses git_buf to load value
config.go      |  8 +++++---
config_test.go | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 63 insertions(+), 3 deletions(-)
*/
func main() {
// After go get -v github.com/libgit2/git2go
// path to git2go repository in your $GOPATH
repoPath := `/home/peter/gopath/src/github.com/libgit2/git2go`
gitRepo, err := git.OpenRepository(repoPath)
if err != nil {
log.Fatal(err)
}
// commit SHA-1 checksum
commitID := `80cf533fe4e48ddfab3015d9570f2833951c1dea`
commitOid, err := git.NewOid(commitID)
if err != nil {
log.Fatal(err)
}
commit, err := gitRepo.LookupCommit(commitOid)
if err != nil {
log.Fatal(err)
}
commitTree, err := commit.Tree()
if err != nil {
log.Fatal(err)
}
options, err := git.DefaultDiffOptions()
if err != nil {
log.Fatal(err)
}
options.IdAbbrev = 40
var parentTree *git.Tree
if commit.ParentCount() > 0 {
parentTree, err = commit.Parent(0).Tree()
if err != nil {
log.Fatal(err)
}
}
gitDiff, err := gitRepo.DiffTreeToTree(parentTree, commitTree, &options)
if err != nil {
log.Fatal(err)
}
// Show all file patch diffs in a commit.
numDeltas, err := gitDiff.NumDeltas()
if err != nil {
log.Fatal(err)
}
for d := 0; d < numDeltas; d++ {
patch, err := gitDiff.Patch(d)
if err != nil {
log.Fatal(err)
}
patchString, err := patch.String()
if err != nil {
log.Fatal(err)
}
log.Printf("\n%s", patchString)
patch.Free()
}
}

Output:

$ go run patchdiffs.go
2016/01/30 18:35:44 
diff --git a/config.go b/config.go
index 9d25e3571de22b4121d66bb88949d0e292f1a836..c4c40281abb85a861ba1bf760011e2990cf151b3 100644
--- a/config.go
+++ b/config.go
@@ -115,18 +115,20 @@ func (c *Config) LookupInt64(name string) (int64, error) {
}
func (c *Config) LookupString(name string) (string, error) {
-	var ptr *C.char
cname := C.CString(name)
defer C.free(unsafe.Pointer(cname))
+	valBuf := C.git_buf{}
+
runtime.LockOSThread()
defer runtime.UnlockOSThread()
-	if ret := C.git_config_get_string(&ptr, c.ptr, cname); ret < 0 {
+	if ret := C.git_config_get_string_buf(&valBuf, c.ptr, cname); ret < 0 {
return "", MakeGitError(ret)
}
+	defer C.git_buf_free(&valBuf)
-	return C.GoString(ptr), nil
+	return C.GoString(valBuf.ptr), nil
}
func (c *Config) LookupBool(name string) (bool, error) {
2016/01/30 18:35:44 
diff --git a/config_test.go b/config_test.go
new file mode 100644
index 0000000000000000000000000000000000000000..e4a2c1f310f1beb9bcb70be50320c53e22417e2a
--- /dev/null
+++ b/config_test.go
@@ -0,0 +1,58 @@
+package git
+
+import (
+	"os"
+	"testing"
+)
+
+func setupConfig() (*Config, error) {
+	var (
+		c   *Config
+		err error
+		p   string
+	)
+
+	p, err = ConfigFindGlobal()
+	if err != nil {
+		return nil, err
+	}
+
+	c, err = OpenOndisk(nil, p)
+	if err != nil {
+		return nil, err
+	}
+
+	c.SetString("foo.bar", "baz")
+
+	return c, err
+}
+
+func cleanupConfig() {
+	os.Remove(tempConfig)
+}
+
+func TestConfigLookupString(t *testing.T) {
+	var (
+		err error
+		val string
+		c   *Config
+	)
+
+	c, err = setupConfig()
+	defer cleanupConfig()
+	if err != nil {
+		t.Errorf("Setup error: '%v'. Expected none\n", err)
+		t.FailNow()
+	}
+	defer c.Free()
+
+	val, err = c.LookupString("foo.bar")
+	if err != nil {
+		t.Errorf("Got error: '%v', expected none\n", err)
+		t.FailNow()
+	}
+
+	if val != "baz" {
+		t.Errorf("Got '%s', expected 'bar'\n", val)
+	}
+}
$