Starting sub-repls from a nrepl client doesn't work (works from lein)

Something funky is going on when trying to start a sub(nested) repl from an nrepl client created with nrepl.cmdline itself.

If we start a JVM process exposing a nrepl server on 7777 like this :

$ clojure -Sdeps '{:deps {nrepl/nrepl {:mvn/version "1.7.0"}}}' -M -m nrepl.cmdline -p 7777

Then we can connect to it from another terminal, and start a sub-repl :

$ clojure -Sdeps '{:deps {nrepl/nrepl {:mvn/version "1.7.0"}}}' -M -m nrepl.cmdline --connect --host localhost --port 7777
nREPL 1.7.0
Clojure 1.12.4
OpenJDK 64-Bit Server VM 24+36-3646
Interrupt: Control+C
Exit:      Control+D or (exit) or (quit)
user=> (clojure.main/repl :prompt #(print "<my-prompt>"))
<my-prompt>(+ 1 2)

The sub-repl starts fine but it doesn't read any characters. Just gets stuck there.

If instead we connect to our nrepl server via the lein client, then it works :

$ lein repl :connect localhost:7777
Connecting to nREPL at localhost:7777
REPL-y 0.5.1, nREPL 1.7.0
Clojure 1.12.4
OpenJDK 64-Bit Server VM 24+36-3646
    Docs: (doc function-name-here)
          (find-doc "part-of-name-here")
  Source: (source function-name-here)
 Javadoc: (javadoc java-object-or-class-here)
    Exit: Control+D or (exit) or (quit)
 Results: Stored in vars *1, *2, *3, an exception in *e

user=> (clojure.main/repl :prompt #(print "<my-prompt>"))
<my-prompt>(+ 1 2)
3
<my-prompt>

I have tried different JVM, Clojure and nrepl versions. Also tried on Linux and Windows with the same behavior.

Start by reproducing the nested REPL through nrepl.cmdline with the documented server and --connect commands, then compare its behavior with lein repl :connect. Trace the nrepl.cmdline client entry point and the sub-repl startup path; done means the nested REPL accepts input and evaluates (+ 1 2) as shown.