cue/load: set the absolute file name when setting source
This means that when the file is decoded, the `internal/encoding.NewDecoder`
logic can find it, even though `internal/encoding.Config` doesn't
contain a directory field to interpret relative file paths.
This fixes a test failure that happens when the modules experiment
flag is enabled by default.
Signed-off-by: Roger Peppe <rogpeppe@gmail.com>
Change-Id: Ia606ce2dc0fca816f3986c24fda96041862b0297
Reviewed-on: https://review.gerrithub.io/c/cue-lang/cue/+/1194830
TryBot-Result: CUEcueckoo <cueckoo@cuelang.org>
Unity-Result: CUE porcuepine <cue.porcuepine@gmail.com>
Reviewed-by: Daniel Martí <mvdan@mvdan.cc>