Debugger stops at unexpected place when using `trace call`

Reproduce with the listed Ruby 3.1.0 and rdbg 1.7.1 steps using the testapp, then follow the trace call entry point and breakpoint at line 9 in app/controllers/students_controller.rb. Confirm the debugger stops at line 9 rather than line 7 after continuing; the issue has no named debugger source file or test.

Your environment

• ruby -v:
• ruby 3.1.0p0 (2021-12-25 revision fb4df44d16) [arm64-darwin21]
• rdbg -v:
• rdbg 1.7.1

To Reproduce

1. Clone https://github.com/ono-max/testapp
2. bundle install
3. rails db:create
4. rails db:migrate
5. bin/rails s

$ bin/rails s
=> Booting Puma
=> Rails 7.0.4.2 application starting in development
=> Run `bin/rails server --help` for more startup options
Puma starting in single mode...
* Puma version: 5.6.5 (ruby 3.0.3-p157) ("Birdie's Version")
*  Min threads: 5
*  Max threads: 5
*  Environment: development
*          PID: 28208
* Listening on http://127.0.0.1:3000
* Listening on http://[::1]:3000
Use Ctrl-C to stop

6. Go to localhost:3000, then it should stop as follows:

...
Use Ctrl-C to stop
Started GET "/" for ::1 at 2023-02-14 01:57:49 +0900
  ActiveRecord::SchemaMigration Pluck (0.1ms)  SELECT "schema_migrations"."version" FROM "schema_migrations" ORDER BY "schema_migrations"."version" ASC
Processing by StudentsController#index as HTML
[1, 10] in ~/workspace/testapp/app/controllers/students_controller.rb
     1| class StudentsController < ApplicationController
     2|   before_action :set_student, only: %i[ show edit update destroy ]
     3|
     4|   # GET /students or /students.json
     5|   def index
=>   6|     binding.break
     7|     student1 = Student.first
     8|     student2 = Student.last
     9|   end
    10|
=>#0	StudentsController#index at ~/workspace/testapp/app/controllers/students_controller.rb:6
  #1	ActionController::BasicImplicitRender#send_action(method="index", args=[]) at ~/.rbenv/versions/3.0.3/lib/ruby/gems/3.0.0/gems/actionpack-7.0.4.2/lib/action_controller/metal/basic_implicit_render.rb:6
  # and 75 frames (use `bt' command for all frames)

7. "trace call"
8. Set a breakpoint at line 9
9. Then continue.
10. Stop at line 7

...
[2, 11] in ~/workspace/testapp/app/controllers/students_controller.rb
     2|   before_action :set_student, only: %i[ show edit update destroy ]
     3|
     4|   # GET /students or /students.json
     5|   def index
     6|     binding.break
=>   7|     student1 = Student.first
     8|     student2 = Student.last
     9|   end
    10|
    11|   # GET /students/1 or /students/1.json
=>#0	StudentsController#index at ~/workspace/testapp/app/controllers/students_controller.rb:7 #=> nil
  #1	ActionController::BasicImplicitRender#send_action(method="index", args=[]) at ~/.rbenv/versions/3.0.3/lib/ruby/gems/3.0.0/gems/actionpack-7.0.4.2/lib/action_controller/metal/basic_implicit_render.rb:6
  # and 75 frames (use `bt' command for all frames)
...

Expected behavior
It should stop at line 9.

Additional context
Add any other context about the problem here.