Fixes #302: Force update can cause a panic

repo/vcs.go

diff --git a/repo/vcs.go b/repo/vcs.go
index 9ff76c7..257340a 100644
--- a/repo/vcs.go
+++ b/repo/vcs.go
@@ -111,6 +111,11 @@
 					msg.Warn("Unable to checkout %s\n", dep.Name)
 					return err
 				}
+
+				repo, err = dep.GetRepo(dest)
+				if err != nil {
+					return err
+				}
 			} else if err != nil {
 				return err
 			} else if repo.IsDirty() {