Quoted keys are treated by the specification like ordinary strings,
so escape codes must be handled as well.
* guix/build/toml.scm (eval-value): Move string escape handling…
(eval-value): …here.
(eval-toml-file): Un-escape quoted keys.
* tests/toml.scm ("parse-toml: Quoted keys with escapes"): New testcase.
Fixes: guix/guix#2414
Change-Id: I612e415cc93207bbdd18b6ec8279255fee16670a
Signed-off-by: Sharlatan Hellseher <sharlatanus@gmail.com>