debug: try write-write file lock.

Author: l-monninger

cite/git/src/repository/lock.rs

@@ -15,6 +15,11 @@ pub(crate) struct Lock {
 	pub lock_file: LockFile,
 }
 
+/// NOTE: I just took a look at how Cargo is handling git concurrency, and they are not...
+///
+/// https://github.com/rust-lang/cargo/blob/3ceb2cb2504fed7446be428c3b8715b696161487/src/cargo/sources/git/source.rs#L445
+/// The clones are single threaded when constructing from the package manager.
+/// Subsequent revision specific activities are performed on locked copies of the repository.
 impl Lock {
 	pub fn new(repository: Repository, lock_file: LockFile) -> Self {
 		Self { repository, lock_file }

cite/git/src/repository/lock/lock_file.rs

@@ -29,7 +29,7 @@ impl LockFile {
 	/// This is optimistic - assumes the file already exists from a previous write operation.
 	pub(crate) fn read(&self) -> Result<FileLock, GitSourceError> {
 		// Read-only lock, no create - assumes file exists from previous write
-		let options = FileOptions::new().write(true);
+		let options = FileOptions::new().read(true).write(true); // DEBUG: it seems setting both read and write makes the lock work?
 
 		// lock is always blocking because this is for builds which don't have concurrency
 		FileLock::lock(self.path.clone(), true, options).map_err(GitSourceError::CreateLockFile)