patch 8.2.3253: channel test fails randomly

Problem:    Channel test fails randomly.
Solution:   Add a sleep after sending the "echoerr" command. (Michael Soyka)

src/testdir/test_channel.py

@@ -114,6 +114,11 @@ class ThreadedTCPRequestHandler(socketserver.BaseRequestHandler):
                         print("sending: {0}".format(cmd))
                         self.request.sendall(cmd.encode('utf-8'))
                         response = "ok"
+                        # Wait a bit, so that the "ex" command is handled
+                        # before the "ch_evalexpr() returns.  Otherwise we are
+                        # outside the try/catch when the "ex" command is
+                        # handled.
+                        time.sleep(0.02)
                     elif decoded[1] == 'bad command':
                         cmd = '["ex","foo bar"]'
                         print("sending: {0}".format(cmd))

src/testdir/test_channel.vim

@@ -253,11 +253,6 @@ endfunc
 func Test_communicate_ipv6()
   CheckIPv6
 
-  " FIXME: this test is very flaky on MS-Windows
-  if has('win32')
-    throw 'Skipped: test is very flaky with MS-Windows'
-  endif
-
   call Test_communicate()
 endfunc
 

src/version.c

@@ -755,6 +755,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    3253,
 /**/
     3252,
 /**/