startup: fix -E/-Es without `-u NONE`

Before this change, -E/-Es without `-u NONE` reads stdin as Ex commands.
It should always read stdin as text (into buffer 1), like this:

    echo foo | nvim -Es +'%p'
    foo
    echo foo | nvim -Es -u NORC +'%p'
    foo

1 files changed, 16 insertions, 0 deletions

diff --git a/test/functional/core/startup_spec.lua b/test/functional/core/startup_spec.lua
index c20ac668c4..ae5e2b4115 100644
--- a/test/functional/core/startup_spec.lua
+++ b/test/functional/core/startup_spec.lua
@@ -157,6 +157,14 @@ describe('startup', function()
     eq(inputstr,
        funcs.system({nvim_prog, '-i', 'NONE', '-Es', '+%print', '-' },
                     input))
+    -- with `-u NORC`
+    eq('thepartycontinues\n',
+       funcs.system({nvim_prog, '-n', '-u', 'NORC', '-Es', '+.print' },
+                    { 'thepartycontinues', '' }))
+    -- without `-u`
+    eq('thepartycontinues\n',
+       funcs.system({nvim_prog, '-n', '-Es', '+.print' },
+                    { 'thepartycontinues', '' }))
 
     --
     -- -es: read stdin as ex-commands
@@ -167,6 +175,14 @@ describe('startup', function()
     eq('line1\nline2\n',
        funcs.system({nvim_prog, '-i', 'NONE', '-es', '-' },
                     input))
+    -- with `-u NORC`
+    eq('  encoding=utf-8\n',
+       funcs.system({nvim_prog, '-n', '-u', 'NORC', '-es' },
+                    { 'set encoding', '' }))
+    -- without `-u`
+    eq('  encoding=utf-8\n',
+       funcs.system({nvim_prog, '-n', '-es' },
+                    { 'set encoding', '' }))
   end)
 end)