cli: migrate trivial uses of op_walk::resolve_op_for_load()

Now heads merging can be turned off by --at-op=@.

cli/src/commands/debug/index.rs

@@ -16,7 +16,6 @@ use std::fmt::Debug;
 use std::io::Write as _;
 
 use jj_lib::default_index::{AsCompositeIndex as _, DefaultReadonlyIndex};
-use jj_lib::op_walk;
 
 use crate::cli_util::CommandHelper;
 use crate::command_error::{internal_error, user_error, CommandError};
@@ -32,13 +31,10 @@ pub fn cmd_debug_index(
     _args: &DebugIndexArgs,
 ) -> Result<(), CommandError> {
     // Resolve the operation without loading the repo, so this command won't
-    // merge concurrent operations and update the index.
+    // update the index.
     let workspace = command.load_workspace()?;
     let repo_loader = workspace.repo_loader();
-    let op = op_walk::resolve_op_for_load(
-        repo_loader,
-        command.global_args().at_operation.as_deref().unwrap_or("@"),
-    )?;
+    let op = command.resolve_operation(ui, repo_loader)?;
     let index_store = repo_loader.index_store();
     let index = index_store
         .get_index_at_op(&op, repo_loader.store())

cli/src/commands/debug/reindex.rs

@@ -16,7 +16,6 @@ use std::fmt::Debug;
 use std::io::Write as _;
 
 use jj_lib::default_index::{AsCompositeIndex as _, DefaultIndexStore};
-use jj_lib::op_walk;
 
 use crate::cli_util::CommandHelper;
 use crate::command_error::{internal_error, user_error, CommandError};
@@ -35,10 +34,7 @@ pub fn cmd_debug_reindex(
     // be rebuilt while loading the repo.
     let workspace = command.load_workspace()?;
     let repo_loader = workspace.repo_loader();
-    let op = op_walk::resolve_op_for_load(
-        repo_loader,
-        command.global_args().at_operation.as_deref().unwrap_or("@"),
-    )?;
+    let op = command.resolve_operation(ui, repo_loader)?;
     let index_store = repo_loader.index_store();
     if let Some(default_index_store) = index_store.as_any().downcast_ref::<DefaultIndexStore>() {
         default_index_store.reinit().map_err(internal_error)?;