MetadataParser: Handle playlist refresh

Untested for now, as we need either a mock file with valid content for
unit testing, or to fiddle with the actual filesystem for functional tests
5 jobs for master in 13 minutes and 34 seconds (queued for 1 second)
Status Job ID Name Coverage
  Build
passed #242480
amd64 debian
build-linux

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passed #242481
win32
build-win32

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passed #242482
win64
build-win64

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  Unit Tests
passed #242483
amd64 debian
unit-tests-linux

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  Functional Tests
passed #242484
amd64 debian
functional-tests-linux

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