[PATCH] fstests: update _filter_btrfs_version

[Eric Sandeen <sandeen@redhat.com>]

The btrfs cmd now sometimes emits "btrfs-progs" not "Btrfs-progs"
as it used to, so update the filter accordingly.

(This fixes a failure on btrfs/006 w/ btrfs-progs v3.19)

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
---

diff --git a/common/filter.btrfs b/common/filter.btrfs
index c9b3f3a..ea047c5 100644
--- a/common/filter.btrfs
+++ b/common/filter.btrfs
@@ -5,7 +5,7 @@
 # Some, but not all, commands emit "Btrfs <version>"
 _filter_btrfs_version()
 {
-	sed -e "s/^Btrfs.*//g"
+	sed -e "s/^[Bb]trfs.*//g"
 }
 
 _filter_devid()