vim-patch:8.0.1672: error during completion causes command to be cancelled

Problem:    Error during completion causes command to be cancelled.
Solution:   Reset did_emsg before waiting for another character. (Tom M.)
72532d354e

src/nvim/ex_getln.c

@@ -510,6 +510,10 @@ static int command_line_check(VimState *state)
   // completion may switch it on.
   quit_more = false;       // reset after CTRL-D which had a more-prompt
 
+  did_emsg = false;        // There can't really be a reason why an error
+                           // that occurs while typing a command should
+                           // cause the command not to be executed.
+
   cursorcmd();             // set the cursor on the right spot
   ui_cursor_shape();
   return 1;

src/nvim/testdir/test_cmdline.vim

@@ -334,6 +334,17 @@ func Test_paste_in_cmdline()
   call feedkeys(":\<C-\>etoupper(getline(1))\<CR>\<C-B>\"\<CR>", 'tx')
   call assert_equal('"ASDF.X /TMP/SOME VERYLONGWORD A;B-C*D ', @:)
   bwipe!
+
+  " Error while typing a command used to cause that it was not executed
+  " in the end.
+  new
+  try
+    call feedkeys(":file \<C-R>%Xtestfile\<CR>", 'tx')
+  catch /^Vim\%((\a\+)\)\=:E32/
+    " ignore error E32
+  endtry
+  call assert_equal("Xtestfile", bufname("%"))
+  bwipe!
 endfunc
 
 func Test_remove_char_in_cmdline()