bugfix: HTTPS Clone fails with remote pointer not found using Go transport (#836) (#842)

Fixes: #836 

Changes:

* adding a weak bool param for Remote
* create a new remote in the smartTransportCallback incase one is not found

clone_test.go

@@ -2,6 +2,7 @@ package git
 
 import (
 	"io/ioutil"
+	"os"
 	"testing"
 )
 
@@ -70,3 +71,17 @@ func TestCloneWithCallback(t *testing.T) {
 	}
 	defer remote.Free()
 }
+
+// TestCloneWithExternalHTTPUrl
+func TestCloneWithExternalHTTPUrl(t *testing.T) {
+
+	path, err := ioutil.TempDir("", "git2go")
+	defer os.RemoveAll(path)
+
+	// clone the repo
+	url := "https://github.com/libgit2/TestGitRepository"
+	_, err = Clone(url, path, &CloneOptions{})
+	if err != nil {
+		t.Fatal("cannot clone remote repo via https, error: ", err)
+	}
+}

remote.go

@@ -182,6 +182,9 @@ type Remote struct {
 	ptr       *C.git_remote
 	callbacks RemoteCallbacks
 	repo      *Repository
+	// weak indicates that a remote is a weak pointer and should not be
+	// freed.
+	weak bool
 }
 
 type remotePointerList struct {
@@ -602,6 +605,9 @@ func (r *Remote) free() {
 // Free releases the resources of the Remote.
 func (r *Remote) Free() {
 	r.repo.Remotes.untrackRemote(r)
+	if r.weak {
+		return
+	}
 	r.free()
 }
 
@@ -1231,3 +1237,12 @@ func freeRemoteCreateOptions(ptr *C.git_remote_create_options) {
 	C.free(unsafe.Pointer(ptr.name))
 	C.free(unsafe.Pointer(ptr.fetchspec))
 }
+
+// createNewEmptyRemote used to get a new empty object of *Remote
+func createNewEmptyRemote() *Remote {
+	return &Remote{
+		callbacks: RemoteCallbacks{},
+		repo:      nil,
+		weak:      false,
+	}
+}

transport.go

@@ -22,7 +22,6 @@ void _go_git_setup_smart_subtransport_stream(_go_managed_smart_subtransport_stre
 */
 import "C"
 import (
-	"errors"
 	"fmt"
 	"io"
 	"reflect"
@@ -306,8 +305,10 @@ func smartTransportCallback(
 	registeredSmartTransport := pointerHandles.Get(handle).(*RegisteredSmartTransport)
 	remote, ok := remotePointers.get(owner)
 	if !ok {
-		err := errors.New("remote pointer not found")
-		return setCallbackError(errorMessage, err)
+		// create a new empty remote and set it
+		// as a weak pointer, so that control stays in golang
+		remote = createNewEmptyRemote()
+		remote.weak = true
 	}
 
 	managed := &managedSmartSubtransport{