Remove git warning: buildx/1633

Signed-off-by: David Gageot <david.gageot@docker.com>
(cherry picked from commit d4a4aaf509)

util/gitutil/gitutil.go

@@ -80,11 +80,11 @@ func (c *Git) RemoteURL() (string, error) {
 }
 
 func (c *Git) FullCommit() (string, error) {
-	return c.clean(c.run("show", "--format=%H", "HEAD", "--quiet"))
+	return c.clean(c.run("show", "--format=%H", "HEAD", "--quiet", "--"))
 }
 
 func (c *Git) ShortCommit() (string, error) {
-	return c.clean(c.run("show", "--format=%h", "HEAD", "--quiet"))
+	return c.clean(c.run("show", "--format=%h", "HEAD", "--quiet", "--"))
 }
 
 func (c *Git) Tag() (string, error) {

util/gitutil/gitutil_test.go

@@ -56,6 +56,20 @@ func TestGitFullCommitErr(t *testing.T) {
 	_, err = c.FullCommit()
 	require.Error(t, err)
 	require.True(t, IsUnknownRevision(err))
+	require.False(t, IsAmbiguousArgument(err))
+}
+
+func TestGitShortCommitErr(t *testing.T) {
+	Mktmp(t)
+	c, err := New()
+	require.NoError(t, err)
+
+	GitInit(c, t)
+
+	_, err = c.ShortCommit()
+	require.Error(t, err)
+	require.True(t, IsUnknownRevision(err))
+	require.False(t, IsAmbiguousArgument(err))
 }
 
 func TestGitTagsPointsAt(t *testing.T) {

util/gitutil/testutil.go

@@ -2,6 +2,7 @@ package gitutil
 
 import (
 	"os"
+	"strings"
 	"testing"
 
 	"github.com/stretchr/testify/require"
@@ -73,3 +74,11 @@ func fakeGit(c *Git, args ...string) (string, error) {
 	allArgs = append(allArgs, args...)
 	return c.clean(c.run(allArgs...))
 }
+
+func IsAmbiguousArgument(err error) bool {
+	if err == nil {
+		return false
+	}
+	errMsg := strings.ToLower(err.Error())
+	return strings.Contains(errMsg, "use '--' to separate paths from revisions")
+}