Distributed: remove backtrace unwrapping from RemoteException (#37937)

base/task.jl

@@ -49,7 +49,7 @@ function showerror(io::IO, ex::CompositeException)
         showerror(io, ex.exceptions[1])
         remaining = length(ex) - 1
         if remaining > 0
-            print(io, string("\n\n...and ", remaining, " more exception(s).\n"))
+            print(io, "\n\n...and ", remaining, " more exception", remaining > 1 ? "s" : "", ".\n")
         end
     else
         print(io, "CompositeException()\n")

stdlib/Distributed/src/process_messages.jl

@@ -54,23 +54,7 @@ remote exception and a serializable form of the call stack when the exception wa
 RemoteException(captured) = RemoteException(myid(), captured)
 function showerror(io::IO, re::RemoteException)
     (re.pid != myid()) && print(io, "On worker ", re.pid, ":\n")
-    showerror(io, get_root_exception(re.captured))
-end
-
-isa_exception_container(ex) = (isa(ex, RemoteException) ||
-                               isa(ex, CapturedException) ||
-                               isa(ex, CompositeException))
-
-function get_root_exception(ex)
-    if isa(ex, RemoteException)
-        return get_root_exception(ex.captured)
-    elseif isa(ex, CapturedException) && isa_exception_container(ex.ex)
-        return get_root_exception(ex.ex)
-    elseif isa(ex, CompositeException) && length(ex.exceptions) > 0 && isa_exception_container(ex.exceptions[1])
-        return get_root_exception(ex.exceptions[1])
-    else
-        return ex
-    end
+    showerror(io, re.captured)
 end
 
 function run_work_thunk(thunk, print_error)

stdlib/Distributed/test/distributed_exec.jl

@@ -439,7 +439,7 @@ catch ex
     # test showerror
     err_str = sprint(showerror, ex)
     err_one_str = sprint(showerror, ex.exceptions[1])
-    @test err_str == err_one_str * "\n\n...and 4 more exception(s).\n"
+    @test err_str == err_one_str * "\n\n...and 4 more exceptions.\n"
 end
 @test sprint(showerror, CompositeException()) == "CompositeException()\n"
 
@@ -1690,16 +1690,14 @@ let (h, t) = Distributed.head_and_tail(Int[], 0)
 end
 
 # issue #35937
-let e
-    try
-        pmap(1) do _
+let e = @test_throws RemoteException pmap(1) do _
             wait(@async error(42))
         end
-    catch ex
-        e = ex
-    end
     # check that the inner TaskFailedException is correctly formed & can be printed
-    @test sprint(showerror, e) isa String
+    es = @show sprint(showerror, e.value)
+    @test contains(es, ":\nTaskFailedException\nStacktrace:\n")
+    @test contains(es, "\n\n    nested task error:")
+    @test_broken contains(es, "\n\n    nested task error: 42\n")
 end
 
 # issue #27429, propagate relative `include` path to workers