TYPO3 Core

When including an external TypoScript file, the very first line of the external file is not always interpreted.

For instance, in my template, I write

<INCLUDE_TYPOSCRIPT: source="FILE: fileadmin/breadcrumb.txt">

with breadcrumb.txt being

-------------------
temp = HMENU
temp.1 = TMENU
temp.1 { # config there
}
-------------------

Sometimes the "temp = HMENU" is forgotten leading to an incomplete TS setup and the temp object not being rendered.

Adding an empty line or a comment at the beginning solves this issue.

I cannot find a way to always reproduce this bug.
(issue imported from #M9963)