patch 8.0.1549: various small problems in test files

Problem:    Various small problems in test files.
Solution:   Include small changes.
diff --git a/src/testdir/test_gui_init.vim b/src/testdir/test_gui_init.vim
index 661bf0c..638708f 100644
--- a/src/testdir/test_gui_init.vim
+++ b/src/testdir/test_gui_init.vim
@@ -17,7 +17,7 @@
 endfunc
 
 " Ignore the "failed to create input context" error.
-call test_ignore_error('E285')
+call test_ignore_error('E285:')
 
 " Start the GUI now, in the foreground.
 gui -f