Make the compare config output look better.

        Cisco IOS incremental-diff output

        No changes:
        !List of Commands:
        end
        !No changes were found

def _normalize_merge_diff_incr(diff):
        """Make the compare config output look better.

        Cisco IOS incremental-diff output

        No changes:
        !List of Commands:
        end
        !No changes were found
        """
        new_diff = []

        changes_found = False
        for line in diff.splitlines():
            if re.search(r"order-dependent line.*re-ordered", line):
                changes_found = True
            elif "No changes were found" in line:
                # IOS in the re-order case still claims "No changes were found"
                if not changes_found:
                    return ""
                else:
                    continue

            if line.strip() == "end":
                continue
            elif "List of Commands" in line:
                continue
            # Filter blank lines and prepend +sign
            elif line.strip():
                if re.search(r"^no\s+", line.strip()):
                    new_diff.append("-" + line)
                else:
                    new_diff.append("+" + line)
        return "\n".join(new_diff)