histedit: end folding message with an LF

This is convenient when running tests dumping the editor content, it
avoids the following output line to be mixed with histedit message.

hgext/histedit.py

@@ -310,7 +310,7 b' def finishfold(ui, repo, ctx, oldctx, ne'
     newmessage = '\n***\n'.join(
         [ctx.description()] +
         [repo[r].description() for r in internalchanges] +
-        [oldctx.description()])
+        [oldctx.description()]) + '\n'
     # If the changesets are from the same author, keep it.
     if ctx.user() == oldctx.user():
         username = ctx.user()

tests/test-histedit-fold-non-commute.t

@@ -91,6 +91,7 b' fix up'
   does not commute with e
   
   
+  
   0 files updated, 0 files merged, 0 files removed, 0 files unresolved
   file e already exists
   1 out of 1 hunks FAILED -- saving rejects to file e.rej