Fix benchsuite issue with newer versions of git

Author: ehuss

benches/benchsuite/src/lib.rs

@@ -125,11 +125,15 @@ impl Fixtures {
             }
         } else {
             fs::create_dir_all(&index).unwrap();
-            git("init --bare");
+            // git 2.48.0 changed the behavior of setting HEAD when doing a
+            // fetch, so let's just force it to match
+            // crates.io-index-archive's default branch. This also accounts
+            // for users who may override init.defaultBranch.
+            git("init --bare --initial-branch=main");
             git("remote add origin https://github.com/rust-lang/crates.io-index-archive");
         }
         git(&format!("fetch origin {}", CRATES_IO_COMMIT));
-        git("branch -f master FETCH_HEAD");
+        git("branch -f main FETCH_HEAD");
     }
 
     /// This unpacks the compressed workspace skeletons into tmp/workspaces.