event-loop: do not set CA_COMMAND_BUSY #9853

CA_COMMAND_BUSY in nv_event() was carried over from Vim nv_cursorhold()
(ref: e5165bae11). It prevents :startinsert from working during a RPC
call, so remove it.

Helped-by: glacambre <me@r4>
closes #7254

src/nvim/normal.c

@@ -8001,7 +8001,6 @@ static void nv_event(cmdarg_T *cap)
   // lists or dicts being used.
   may_garbage_collect = false;
   multiqueue_process_events(main_loop.events);
-  cap->retval |= CA_COMMAND_BUSY;       // don't call edit() now
   finish_op = false;
 }
 

test/functional/api/vim_spec.lua

@@ -56,6 +56,13 @@ describe('API', function()
     eq(2, eval('1+1'))
   end)
 
+  it('does not set CA_COMMAND_BUSY #7254', function()
+    nvim('command', 'split')
+    nvim('command', 'autocmd WinEnter * startinsert')
+    nvim('command', 'wincmd w')
+    eq({mode='i', blocking=false}, nvim("get_mode"))
+  end)
+
   describe('nvim_command', function()
     it('works', function()
       local fname = helpers.tmpname()
@@ -83,7 +90,7 @@ describe('API', function()
     end)
 
     it('VimL execution error: fails with specific error', function()
-      local status, rv = pcall(nvim, "command_output", "buffer 23487")
+      local status, rv = pcall(nvim, "command", "buffer 23487")
       eq(false, status)                 -- nvim_command() failed.
       eq("E86: Buffer 23487 does not exist", string.match(rv, "E%d*:.*"))
       eq('', eval('v:errmsg'))  -- v:errmsg was not updated.