`break` should respect current frame.

[ko1]

Your environment

• ruby -v: 2.7
• rdbg -v: 1.4

Describe the bug

When the current frame is not a top-frame, but b <line> makes a breakpoint on the top frame.

To Reproduce

# t1.rb

require_relative 't2'

foo

p 1
p 2
p 3

# t2.rb
def foo
 
end

$ exe/rdbg target.rb -e 'b t2.rb:3'
(rdbg) up # command
=> 4| foo
(rdbg) b 7 # break command
#1 BP - Line (pending) t2.rb:7 <--- it should be t1.rb:7