libgit2: Adhoc fix for darwin

When running in MacOS, the util.Walk func may incorrectly
say that the current dir is not inside the workdir set in
the fs. To workaround the issue we check for the error and
ensure that the path is the same as the
workdir set.

Signed-off-by: Paulo Gomes <paulo.gomes@weave.works>

git/libgit2/client.go

@@ -24,6 +24,7 @@ import (
 	"io"
 	"net/url"
 	"os"
+	"runtime"
 	"strings"
 	"time"
 
@@ -313,9 +314,21 @@ func (l *Client) Commit(info git.Commit, commitOpts ...repository.CommitOption)
 	}
 	defer index.Free()
 
-	if err = util.Walk(l.repoFS, "",
+	walkPath := ""
+	// Workaround bug in MacOS.
+	if runtime.GOOS == "darwin" {
+		walkPath = l.path
+	}
+
+	if err = util.Walk(l.repoFS, walkPath,
 		func(path string, info os.FileInfo, err error) error {
 			if err != nil {
+				// Workaround bug in MacOS. This code is being sunsetting
+				// soon as part of libgit2 decommissioning, therefore no
+				// need for a more robust fix.
+				if strings.Contains(err.Error(), "path outside working dir") && path == l.path {
+					return nil
+				}
 				return err
 			}
 			// skip symlinks and any files that are within ".git/"