transplant: Add trailing LF in tmp file for filtering

Transplant filtering used a tmp file ending with the (stripped) commit
message and thus no final LF. Text files not ending with LF is usually
not used on Unix and is thus wrong ;-)

The missing LF had bad consequences because Solaris sed chokes on
unterminated input lines, so

  echo -n foo|sed 's,o,0,g'

doesn't output anything, and the filter used in tests/test-transplant
thus stripped the last (and only) line in the message away on solaris.

hgext/transplant.py

@@ -182,7 +182,7 b' class transplanter(object):'
         fp.write("# HG changeset patch\n")
         fp.write("# User %s\n" % user)
         fp.write("# Date %d %d\n" % date)
-        fp.write(changelog[4])
+        fp.write(msg + '\n')
         fp.close()
 
         try: