This will only pass-through the powered-by.html url, but it should redirect it. It also doesn't address the /powered-by/ url, which wouldn't be available without a passthrough. Should probably be this:

```apache
RewriteRule ^/(\w{2,3}(?:-\w{2}(?:-mac)?)?/)?projects/powered-by.html$ /$1projects/powered-by/ [L,R=301]
RewriteRule ^/(\w{2,3}(?:-\w{2}(?:-mac)?)?/)?projects/powered-by(/?)$ /b/$1projects/powered-by$2 [PT]
```