ldap,mysql,pgsql: use bash pipefail option so that failed dumps are reported as such

This should fix Redmine bug #1340.

This option makes pipelines return as status the value of the last (rightmost)
command to exit with a non-zero status, or zero if all commands exit
successfully. See bash(1) for details.

E.g. this prevents the following from exiting with status 0 (!) if pg_dumpall
fails:

        pg_dumpall | gzip

1 files changed, 6 insertions, 0 deletions

diff --git a/ChangeLog b/ChangeLog
index 130a544..18ed157 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -15,6 +15,8 @@ version 0.9.7 -- UNRELEASED
     handler changes
 	ldap:
 	 . Use gzip's --rsyncable option.
+	 . Use bash pipefail option when needed so that failed dumps are
+	   reported as such.
 	maildir:
 	 . fix location of deleted_on file
 	 . add missing destid_file options to ssh connections
@@ -32,10 +34,14 @@ version 0.9.7 -- UNRELEASED
 	 . Use gzip's --rsyncable option.
 	 . Quote output filenames to support shell meta-characters in
 	   database names.
+	 . Use bash pipefail option when needed so that failed dumps are
+	   reported as such.
 	pgsql:
 	 . Use gzip's --rsyncable option.
 	 . Quote output filenames to support shell meta-characters in
 	   database names.
+	 . Use bash pipefail option when needed so that failed dumps are
+	   reported as such.
 	sys:
 	 . New luksheaders option (default=disabled) to backup the Luks header
 	   of every Luks device.