contrib/editmergeps.bat

unamend: fix command summary line

Before this patch, the docstring started with a newline, which led the
summary line (shown in e.g. `hg help -c`) to be blank.

Differential Revision: https://phab.mercurial-scm.org/D1943

@echo off
powershell -NoProfile -ExecutionPolicy unrestricted -Command "& '%~dp0\editmergeps.ps1' %*"