spawn prompt! to free it from sticky repl task

stdlib/REPL/src/LineEdit.jl

@@ -2740,10 +2740,12 @@ end
 
 function run_interface(terminal::TextTerminal, m::ModalInterface, s::MIState=init_state(terminal, m))
     while !s.aborted
-        buf, ok, suspend = prompt!(terminal, m, s)
+        # spawn this so because the main repl task is sticky (due to use of @async and _wait2)
+        # and we want to not block typing when the repl task thread is busy
+        buf, ok, suspend = fetch(Threads.@spawn :interactive prompt!(terminal, m, s))
         while suspend
             @static if Sys.isunix(); ccall(:jl_repl_raise_sigtstp, Cint, ()); end
-            buf, ok, suspend = prompt!(terminal, m, s)
+            buf, ok, suspend = fetch(Threads.@spawn :interactive prompt!(terminal, m, s))
         end
         Base.invokelatest(mode(state(s)).on_done, s, buf, ok)
     end
@@ -2829,7 +2831,7 @@ function prompt!(term::TextTerminal, prompt::ModalInterface, s::MIState = init_s
         activate(prompt, s, term, term)
         old_state = mode(s)
         l = Base.ReentrantLock()
-        t = @async while true
+        t = Threads.@spawn :interactive while true
             wait(s.async_channel)
             status = @lock l begin
                 fcn = take!(s.async_channel)