patch 7.4.2031
Problem:    The list_lbr_utf8 test fails if ~/.vim/syntax/c.vim sets
            'textwidth' to a non-zero value. (Oyvind A. Holm)
Solution:   Add a setup.vim file that sets 'runtimepath' and $HOME to a safe
            value. (partly by Christian Brabandt, closes #912)
diff --git a/src/testdir/dos.vim b/src/testdir/dos.vim
index 27764db..3ea6ab2 100644
--- a/src/testdir/dos.vim
+++ b/src/testdir/dos.vim
@@ -5,3 +5,5 @@
 if executable("cmd.exe")
    set shell=cmd.exe
 endif
+
+source setup.vim