When creating a project, primary slug is generated by project name.
If same as primary tag is added in "Additional Hashtags' field, exception is thrown.
Steps to reproduce:
# Open "create project" page.
# Input same single word value to **Name** and **Additional Hashtags** fields.
# Click **Save**.
Result:
```
Unhandled Exception ("AphrontDuplicateKeyQueryException")
#1062: Duplicate entry 'xyz' for key 'key_slug'
```
Expected result:
Project created and tag ignored silently. Tag will appear in project hashtags list still, because it will be created by name.