one more intermittent test failure

[David Bremner]

Hi All;

Since we've had some luck cleaning up intermittent test failures, I
thought it would be nice if we could fix this one. We've seen it on the
buildbot from time to time, and it's pretty easy to duplicate with 

make test-binaries && count=0 && while ./new; do 
count=$(( count + 1))
echo $count
done


 FAIL   Ignore files and directories specified in new.ignore (multiple occurrences)
	--- new.22.expected	2013-12-23 00:41:18.015910311 +0000
	+++ new.22.output	2013-12-23 00:41:18.015910311 +0000
	@@ -5,9 +5,6 @@
	 (D) add_files_recursive, pass 1: explicitly ignoring /home/bremner/software/upstream/notmuch/test/tmp.new/mail/one/two/ignored_file
	 (D) add_files_recursive, pass 1: explicitly ignoring /home/bremner/software/upstream/notmuch/test/tmp.new/mail/one/two/three/.git
	 (D) add_files_recursive, pass 1: explicitly ignoring /home/bremner/software/upstream/notmuch/test/tmp.new/mail/one/two/three/ignored_file
	-(D) add_files_recursive, pass 2: explicitly ignoring /home/bremner/software/upstream/notmuch/test/tmp.new/mail/.git
	-(D) add_files_recursive, pass 2: explicitly ignoring /home/bremner/software/upstream/notmuch/test/tmp.new/mail/.ignored_hidden_file
	-(D) add_files_recursive, pass 2: explicitly ignoring /home/bremner/software/upstream/notmuch/test/tmp.new/mail/ignored_file
	 (D) add_files_recursive, pass 2: explicitly ignoring /home/bremner/software/upstream/notmuch/test/tmp.new/mail/one/ignored_file
	 (D) add_files_recursive, pass 2: explicitly ignoring /home/bremner/software/upstream/notmuch/test/tmp.new/mail/one/two/ignored_file
	 (D) add_files_recursive, pass 2: explicitly ignoring /home/bremner/software/upstream/notmuch/test/tmp.new/mail/one/two/three/.git