working_copy: mark commit_id field in proto reserved

By marking it reserved, we prevent accidental use. We can still read
working copy protos that have the field.

lib/src/local_working_copy.rs

@@ -1533,7 +1533,6 @@ impl LocalWorkingCopy {
         let proto = crate::protos::working_copy::Checkout {
             operation_id: operation_id.to_bytes(),
             workspace_id: workspace_id.as_str().to_string(),
-            ..Default::default()
         };
         let mut file = OpenOptions::new()
             .create_new(true)
@@ -1638,7 +1637,6 @@ impl LocalWorkingCopy {
         self.write_proto(crate::protos::working_copy::Checkout {
             operation_id: self.operation_id().to_bytes(),
             workspace_id: self.workspace_id().as_str().to_string(),
-            ..Default::default()
         });
     }
 

lib/src/protos/working_copy.proto

@@ -66,8 +66,5 @@ message Checkout {
   // TODO: Is it better to make this a UUID and a have map that to a name in
   // config? That way users can rename a workspace.
   string workspace_id = 3;
-  // The checked-out commit, which can be viewed as a cache of the working-copy
-  // commit ID recorded in `operation_id`'s operation. No longer used.
-  // TODO: Delete this mid 2022 or so
-  bytes commit_id = 1;
+  reserved 1;
 }

lib/src/protos/working_copy.rs

@@ -71,11 +71,6 @@ pub struct Checkout {
     /// config? That way users can rename a workspace.
     #[prost(string, tag = "3")]
     pub workspace_id: ::prost::alloc::string::String,
-    /// The checked-out commit, which can be viewed as a cache of the working-copy
-    /// commit ID recorded in `operation_id`'s operation. No longer used.
-    /// TODO: Delete this mid 2022 or so
-    #[prost(bytes = "vec", tag = "1")]
-    pub commit_id: ::prost::alloc::vec::Vec<u8>,
 }
 #[derive(Clone, Copy, Debug, PartialEq, Eq, Hash, PartialOrd, Ord, ::prost::Enumeration)]
 #[repr(i32)]