Set the 'RootFolder' only if it contains 'data' dir

It can happen that vendored package, does not contain
data directory (ie. when using 'go mod vendor', which
does not vendor not linked directories)
This should solve it, setting a directory as
'RootFolder' only if it contains 'data' subdirectory

Signed-off-by: David Pordomingo <[email protected]>

Author: dpordomingo

fixtures.go

@@ -328,8 +328,7 @@ func Init() error {
 		rf := filepath.Join(
 			src, "gopkg.in/src-d/go-git-fixtures.v3",
 		)
-
-		if _, err := os.Stat(rf); err == nil {
+		if _, err := os.Stat(filepath.Join(rf, DataFolder)); err == nil {
 			RootFolder = rf
 			return nil
 		}
@@ -338,8 +337,11 @@ func Init() error {
 	// Try the modules local cache
 	if dir, err := os.Getwd(); err == nil {
 		if pkg, err := build.Default.Import("gopkg.in/src-d/go-git-fixtures.v3", dir, build.FindOnly); err == nil {
-			RootFolder = pkg.Dir
-			return nil
+			if _, err := os.Stat(filepath.Join(pkg.Dir, DataFolder)); err == nil {
+				RootFolder = pkg.Dir
+				return nil
+			}
+
 		}
 	}