Merge pull request #557 from Masterminds/fix/550

Fixed #550: There was opportunity for nil pointers in lock
diff --git a/cfg/lock.go b/cfg/lock.go
index 62d08ef..c03ac41 100644
--- a/cfg/lock.go
+++ b/cfg/lock.go
@@ -196,7 +196,7 @@
 		Hash:       hash,
 		Updated:    time.Now(),
 		Imports:    make([]*Lock, len(ds)),
-		DevImports: make([]*Lock, len(tds)),
+		DevImports: make([]*Lock, 0),
 	}
 
 	for i := 0; i < len(ds); i++ {
@@ -218,7 +218,7 @@
 			}
 		}
 		if !found {
-			lf.DevImports[i] = LockFromDependency(tds[i])
+			lf.DevImports = append(lf.DevImports, LockFromDependency(tds[i]))
 		}
 	}