Warn user about the working copy when configuring the author #13337

Job	Run time
build (ubuntu-latest)	4m 26s
Build jj-lib without Git support	45s
build (macos-14)	3m 38s
build (windows-latest)	8m 48s
cargo-deny (advisories)	22s
cargo-deny (bans licenses sources)	24s
build (ubuntu-latest, --all-features)	5m 37s
Check protos	32s
Check that MkDocs can build the docs	20s
Clippy check	2m 27s
Check that MkDocs can build the docs with Poetry 1.8	25s
Check formatting	14s
	27m 58s

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