diff --git a/rust/hg-core/Cargo.toml b/rust/hg-core/Cargo.toml
--- a/rust/hg-core/Cargo.toml
+++ b/rust/hg-core/Cargo.toml
@@ -36,8 +36,6 @@ log = "0.4.17"
 memmap2 = { version = "0.5.8", features = ["stable_deref_trait"] }
 zstd = "0.12"
 format-bytes = "0.3.0"
-# once_cell 1.15 uses edition 2021, while the heptapod CI
-# uses an old version of Cargo that doesn't support it.
 once_cell = "1.16.0"
 
 # We don't use the `miniz-oxide` backend to not change rhg benchmarks and until