Fix bug that "record on" doesn't work after stopping record once

[ono-max]

Debugger doesn't work after stopping record once as follows:

$ exe/rdbg g.rb
[1, 6] in g.rb
=>   1| a=1
     2|
     3| b=1
     4|
     5| c=1
     6| p a
=>#0	<main> at g.rb:1
(rdbg) record on    # command
Recorder for #<Thread:0x000000013007bc60 run>: on (0 records)
(rdbg) record off    # command
Recorder for #<Thread:0x000000013007bc60 run>: off
(rdbg) record on    # command
Recorder for #<Thread:0x000000013007bc60 run>: off
(rdbg) b 5    # break command
#0  BP - Line  /Users/s15236/workspace/debug/g.rb:5 (line)
(rdbg) c    # continue command
[1, 6] in g.rb
     1| a=1
     2|
     3| b=1
     4|
=>   5| c=1
     6| p a
=>#0	<main> at g.rb:5

Stop by #0  BP - Line  /Users/s15236/workspace/debug/g.rb:5 (line)
(rdbg) step back    # command
Can not step back more.

Expected behavior

$ exe/rdbg g.rb
[1, 6] in g.rb
=>   1| a=1
     2|
     3| b=1
     4|
     5| c=1
     6| p a
=>#0	<main> at g.rb:1
(rdbg) record on    # command
Recorder for #<Thread:0x000000014487bc58 run>: on (0 records)
(rdbg) b 5    # break command
#0  BP - Line  /Users/s15236/workspace/debug/g.rb:5 (line)
(rdbg) c    # continue command
[1, 6] in g.rb
     1| a=1
     2|
     3| b=1
     4|
=>   5| c=1
     6| p a
=>#0	<main> at g.rb:5

Stop by #0  BP - Line  /Users/s15236/workspace/debug/g.rb:5 (line)
(rdbg) step back    # command
[replay] [1, 6] in g.rb
[replay]      1| a=1
[replay]      2|
[replay]      3| b=1
[replay]      4|
[replay] =>   5| c=1
[replay]      6| p a
[replay] =>#0	<main> at g.rb:5
Really quit? [Y/n] 1D

[st0012]

Can you add a test for it? It can just be the example in the description. Thx