creating new repository with REST API makes empty name (BB-9633)

Issue #8556 resolved
yui test
created an issue

I found a bug of REST API.

I tried this way:
https://confluence.atlassian.com/display/BITBUCKET/repository+Resource

"name"
"The name for the repository. When omitted, this assumes that value of the repo_slug part of the URL (optional)."

But I haven't specified "name", it was managed as "" (zero bytes string as repository name).
and some dashboard's history was broken.
many 500 errors were happen.