add path to cookie so multiple installations on one root possible.

Not sure this is correct but it appears to make the cookie have the same path as Core 1.3.5 did. I assume this is important when having multiple installations on the same root. 

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | na
| Refs tickets  | na
| Fixed tickets | na
| License       | MIT
| Doc PR        | na