elog/collect_ebuild_messages: strip trailing \n

This fixes unintended extra blank lines since commit
1c8ff00a26b0e2e3627e9c552374f71235ee6c39.
diff --git a/pym/portage/elog/messages.py b/pym/portage/elog/messages.py
index 50e0ab1..f5232d3 100644
--- a/pym/portage/elog/messages.py
+++ b/pym/portage/elog/messages.py
@@ -47,6 +47,7 @@
 			encoding=_encodings['fs'], errors='strict'),
 			mode='r', encoding=_encodings['repo.content'], errors='replace')
 		for l in f:
+			l = l.rstrip('\n')
 			if not l:
 				continue
 			try: