[PATCH] t9010: Open backflow FIFO once to work around kernel race condition

[Anders Kaseorg <andersk@MIT.EDU>]

Linux’s implementation of open() on FIFOs suffers from a race
condition (see http://marc.info/?l=linux-kernel&m=134071285509470 )
that causes t9010-svn-fe.sh to occasionally fail with
  t9010-svn-fe.sh: 27: eval: cannot create backflow: Interrupted system call
Although I can’t reproduce this locally, it happens particularly often
on the Launchpad PPA builders.

Sidestep this problem by opening the backflow FIFO once for
read+write.  Also, replace the stream FIFO with a shell pipe so we
don’t have to do manual process management.

Signed-off-by: Anders Kaseorg <andersk@mit.edu>
---
 t/t9010-svn-fe.sh | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/t/t9010-svn-fe.sh b/t/t9010-svn-fe.sh
index b7eed24..c52a7de 100755
--- a/t/t9010-svn-fe.sh
+++ b/t/t9010-svn-fe.sh
@@ -11,9 +11,9 @@ reinit_git () {
 		return 127
 	fi
 	rm -fr .git &&
-	rm -f stream backflow &&
+	rm -f backflow &&
 	git init &&
-	mkfifo stream backflow
+	mkfifo backflow
 }
 
 try_dump () {
@@ -22,10 +22,9 @@ try_dump () {
 	maybe_fail_fi=${3:+test_$3} &&
 
 	{
-		$maybe_fail_svnfe test-svn-fe "$input" >stream 3<backflow &
-	} &&
-	$maybe_fail_fi git fast-import --cat-blob-fd=3 <stream 3>backflow &&
-	wait $!
+		$maybe_fail_svnfe test-svn-fe "$input" |
+		$maybe_fail_fi git fast-import --cat-blob-fd=3
+	} 3<>backflow
 }
 
 properties () {
-- 
1.7.11.1