wic/engine: Add missing newline

On some hosts the wic.Wic2.test_wic_cp_ext selftest was failing as files weren't
being copied into the rootfs with "wic cp". This was due to a bug added by:

http://git.yoctoproject.org/cgit.cgi/poky/commit/?id=89d4a8df074598cfb3a76e41db7c45d845afd961

where there should be a second newline added at the end of the expression due
to the difference in the way echo -e and printf behave.

[YOCTO #13237]

(From OE-Core rev: 2f3adb21cc5067458a12964d0bde235966a20a60)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

scripts/lib/wic/engine.py

@@ -338,7 +338,7 @@ class Disk:
     def copy(self, src, pnum, path):
         """Copy partition image into wic image."""
         if self.partitions[pnum].fstype.startswith('ext'):
-            cmd = "printf 'cd {}\nwrite {} {}' | {} -w {}".\
+            cmd = "printf 'cd {}\nwrite {} {}\n' | {} -w {}".\
                       format(path, src, os.path.basename(src),
                              self.debugfs, self._get_part_image(pnum))
         else: # fat