[HttpKernel] fix HInclude src (closes #8951)

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #8951
| License       | MIT
| Doc PR        | n/a

fixes a regression introduced in #8879