erp5.mariadb: Use --single-transaction with mysqldump.

Otherwise, mysqldump locks all tables wich cause a (noticeable or not,
depending on backup duration and site load at backup time) total site
unavailability.

stack/erp5/buildout.cfg

@@ -172,7 +172,7 @@ context =
 [template-mariadb]
 < = download-base
 filename = instance-mariadb.cfg.in
-md5sum = 000d5e38bd5f5c8869e69f1232d12e56
+md5sum = a6e40c2d9f223e5d29d80d81a35d422f
 link-binary =
   ${coreutils:location}/bin/basename
   ${coreutils:location}/bin/cat

stack/erp5/instance-mariadb.cfg.in

@@ -41,7 +41,7 @@ frequency = 0 22 * * *
 #   can be fully restored.
 # master-data: use value "2" as we are not in a replication case
 #}
-command = "${binary-wrap-mysqldump:wrapper-path}" -u root --all-databases {% if incremental_backup_retention_days > -1 %}--flush-logs --master-data=2 {% endif %}| {{ parameter_dict['gzip-location'] }}/bin/gzip > "${directory:mariadb-backup-full}/$({{ parameter_dict['coreutils-location'] }}/bin/date "+%Y%m%d%H%M%S").sql.gz"
+command = "${binary-wrap-mysqldump:wrapper-path}" -u root --all-databases --single-transaction {% if incremental_backup_retention_days > -1 %}--flush-logs --master-data=2 {% endif %}| {{ parameter_dict['gzip-location'] }}/bin/gzip > "${directory:mariadb-backup-full}/$({{ parameter_dict['coreutils-location'] }}/bin/date "+%Y%m%d%H%M%S").sql.gz"
 {# KEEP GLOB PATTERN IN SYNC with generated filenames above
 #           YYYYmmddHHMMSS -#}
 file-glob = ??????????????.sql.gz