fixed graph_lock.py - lock_node(): consider context

[SzBosch]

fixes #13775

Changelog: Bugfix: Fixed graph_lock.py - lock_node(): consider context of build_require from lockfile.
Docs: Omit

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[memsharded]

Fantastic, thanks very much, happy to know that this bug seems possible to fix.
I will be contributing the tests later, and I have assigned it for next 1.60, that seems will be released likely end of next week, beginning of the following one.