Add test for dos noeol

See #862.

test/test_gitgutter.vim

@@ -59,6 +59,7 @@ function SetUp()
         \ " && cp ../fixture.foo .".
         \ " && cp ../fixture.txt .".
         \ " && cp ../fixture_dos.txt .".
+        \ " && cp ../fixture_dos_noeol.txt .".
         \ " && git add . && git commit -m 'initial'".
         \ " && git config diff.mnemonicPrefix false")
   execute ':cd' s:test_repo
@@ -408,6 +409,12 @@ function Test_preview_dos()
 endfunction
 
 
+function Test_dos_noeol()
+  edit! fixture_dos_noeol.txt
+  GitGutter
+
+  call s:assert_signs([], 'fixture_dos_noeol.txt')
+endfunction
 
 
 function Test_hunk_stage()