Fix route rename descendants if route.name is blank

What does this MR do?

Fix route rename descendants if route.name is blank

Are there points in the code the reviewer needs to double check?

no

Why was this MR needed?

Too prevent 500 error when one of nested routes has empty name (which is ok)

Does this MR meet the acceptance criteria?

• Tests
  • Added for this feature/bug
  • All builds are passing
• Conform by the merge request performance guides
• Conform by the style guides
• Branch has no merge conflicts with master (if it does - rebase it please)
• Squashed related commits together

What are the relevant issue numbers?

https://gitlab.com/gitlab-org/gitlab-ce/issues/2772

marked the task Added for this feature/bug as completed

marked the task Conform by the merge request performance guides as completed

marked the task Conform by the style guides as completed

marked the task Branch has no merge conflicts with master (if it does - rebase it please) as completed

marked the task Squashed related commits together as completed

enabled an automatic merge when the pipeline for 0a4b8191 succeeds

canceled the automatic merge

added 1 commit

• 4d40c3c3 - Fix route rename descendants if route.name is blank

Compare with previous version

enabled an automatic merge when the pipeline for 4d40c3c3 succeeds

merged

mentioned in commit a6a3df64

marked the task All builds are passing as completed