don't emit spurious error messages

stdlib/Distributed/src/cluster.jl

@@ -253,6 +253,13 @@ end
 
 Base.showerror(io::IO, e::LaunchWorkerError) = print(io, e.msg)
 
+function read_worker_host_port_throw_error(leader, msg)
+    for line in leader
+        println("\tFrom failed worker startup:\t", line)
+    end
+    throw(LaunchWorkerError(msg))
+end
+
 # The default TCP transport relies on the worker listening on a free
 # port available and printing its bind address and port.
 # The master process uses this to connect to the worker and subsequently
@@ -272,40 +279,31 @@ function read_worker_host_port(io::IO)
 
     ntries = 1000
     leader = String[]
-    try
-        while ntries > 0
-            readtask = @async readline(io)
-            yield()
-            while !istaskdone(readtask) && ((time() - t0) < timeout)
-                sleep(0.05)
-            end
-            !istaskdone(readtask) && break
-
-            conninfo = fetch(readtask)
-            if isempty(conninfo) && !isopen(io)
-                throw(LaunchWorkerError("Unable to read host:port string from worker. Launch command exited with error?"))
-            end
+    while ntries > 0
+        readtask = @async readline(io)
+        yield()
+        while !istaskdone(readtask) && ((time() - t0) < timeout)
+            sleep(0.05)
+        end
+        !istaskdone(readtask) && break
 
-            ntries -= 1
-            bind_addr, port = parse_connection_info(conninfo)
-            if !isempty(bind_addr)
-                return bind_addr, port
-            end
+        conninfo = fetch(readtask)
+        isempty(conninfo) && !isopen(io) && read_worker_host_port_throw_error(leader,
+                "Unable to read host:port string from worker. Launch command exited with error?")
 
-            # collect unmatched lines
-            push!(leader, conninfo)
-        end
-        close(io)
-        if ntries > 0
-            throw(LaunchWorkerError("Timed out waiting to read host:port string from worker."))
-        else
-            throw(LaunchWorkerError("Unexpected output from worker launch command. Host:port string not found."))
-        end
-    finally
-        for line in leader
-            println("\tFrom failed worker startup:\t", line)
+        ntries -= 1
+        bind_addr, port = parse_connection_info(conninfo)
+        if !isempty(bind_addr)
+            return bind_addr, port
         end
+
+        # collect unmatched lines
+        push!(leader, conninfo)
     end
+    close(io)
+    read_worker_host_port_throw_error(leader, ntries>0 ?
+            "Timed out waiting to read host:port string from worker." :
+            "Unexpected output from worker launch command. Host:port string not found.")
 end
 
 function parse_connection_info(str)