rustPlatform.fetchCargoTarball: fail on git dependencies

The reason is that we can not expect the extended logic run on git
dependencies starting from Cargo 1.68 to be reproducible in future
 versions, and thus the output hash would not be sufficiently stable.
rust-lang/cargo#11414

pkgs/build-support/rust/fetch-cargo-tarball/default.nix

@@ -76,6 +76,17 @@ in stdenv.mkDerivation ({
     # Override the `http.cainfo` option usually specified in `.cargo/config`.
     export CARGO_HTTP_CAINFO=${cacert}/etc/ssl/certs/ca-bundle.crt
 
+    if grep '^source = "git' Cargo.lock; then
+        echo
+        echo "ERROR: The Cargo.lock contains git dependencies"
+        echo
+        echo "This is currently not supported in the fixed-output derivation fetcher."
+        echo "Use cargoLock.lockFile / importCargoLock instead."
+        echo
+
+        exit 1
+    fi
+
     cargo vendor $name --respect-source-config | cargo-vendor-normalise > $CARGO_CONFIG
 
     # Create an empty vendor directory when there is no dependency to vendor