Fix possible race condition

Author: lafriks

models/repo_branch.go

@@ -92,14 +92,14 @@ func (repo *Repository) CheckBranchName(name string) error {
 
 // CreateNewBranch creates a new repository branch
 func (repo *Repository) CreateNewBranch(doer *User, oldBranchName, branchName string) (err error) {
+	repoWorkingPool.CheckIn(com.ToStr(repo.ID))
+	defer repoWorkingPool.CheckOut(com.ToStr(repo.ID))
+
 	// Check if branch name can be used
 	if err := repo.CheckBranchName(branchName); err != nil {
 		return err
 	}
 
-	repoWorkingPool.CheckIn(com.ToStr(repo.ID))
-	defer repoWorkingPool.CheckOut(com.ToStr(repo.ID))
-
 	localPath := repo.LocalCopyPath()
 
 	if err = discardLocalRepoBranchChanges(localPath, oldBranchName); err != nil {
@@ -157,14 +157,14 @@ func (repo *Repository) updateLocalCopyToCommit(commit string) error {
 
 // CreateNewBranchFromCommit creates a new repository branch
 func (repo *Repository) CreateNewBranchFromCommit(doer *User, commit, branchName string) (err error) {
+	repoWorkingPool.CheckIn(com.ToStr(repo.ID))
+	defer repoWorkingPool.CheckOut(com.ToStr(repo.ID))
+
 	// Check if branch name can be used
 	if err := repo.CheckBranchName(branchName); err != nil {
 		return err
 	}
 
-	repoWorkingPool.CheckIn(com.ToStr(repo.ID))
-	defer repoWorkingPool.CheckOut(com.ToStr(repo.ID))
-
 	localPath := repo.LocalCopyPath()
 
 	if err = repo.updateLocalCopyToCommit(commit); err != nil {