Keep new changes on right

Saves and restores splitright option
Backported from 512df2948

vimtabdiff.py

@@ -67,6 +67,11 @@ def main():
     args = parse_args()
     vimCmdFile = tempfile.NamedTemporaryFile(mode='w', delete=False)
     with vimCmdFile:
+        cmds = f"""
+        let s:spr = &splitright
+        set splitright
+        """
+        print(cmds, file=vimCmdFile)
         for a, b in get_file_pairs(args.pathA, args.pathB):
             aPath = a.resolve() if a else os.devnull
             bPath = b.resolve() if b else os.devnull
@@ -74,6 +79,10 @@ def main():
                 f"tabedit {aPath} | diffthis | vsp {bPath} | diffthis | diffupdate",
                 file=vimCmdFile)
         cmds = f"""
+        let &splitright = s:spr
+        tabdo windo :1
+        tabdo windo diffthis
+        tabdo windo diffupdate
         tabfirst | tabclose
         call delete("{vimCmdFile.name}")
         """