Comment 2 for bug 1467424

This is easy to confirm:

[openxs@chief percona-xtrabackup-2.2]$ grep -rn XB_VERSION_EXTRA *
cmake/mysql_version.cmake:72: MYSQL_GET_CONFIG_VALUE("XB_VERSION_EXTRA" XB_EXTRA_VERSION XB_VERSION)
storage/innobase/xtrabackup/utils/build-rpm.sh:100:XTRABACKUP_VERSION="${XB_VERSION_MAJOR}.${XB_VERSION_MINOR}.${XB_VERSION_PATCH}${XB_VERSION_EXTRA}"
storage/innobase/xtrabackup/utils/build-rpm.sh:140:if [ -z "${XB_VERSION_EXTRA:-}" ]; then
storage/innobase/xtrabackup/utils/build-rpm.sh:144: EXTRAVER=${XB_VERSION_EXTR }
storage/innobase/xtrabackup/utils/build-rpm.sh:145: RPM_EXTRAVER=.${XB_VERSION_EXTRA#-}
storage/innobase/xtrabackup/utils/build-rpm.sh:149:sed -i "s:@@XB_VERSION_EXTRA@@:${EXTRAVER}:g" SPECS/percona-xtrabackup.spec
storage/innobase/xtrabackup/utils/build-binary.sh:83:XTRABACKUP_VERSION="${XB_VERSION_MAJOR}.${XB_VERSION_MINOR}.${XB_VERSION_PATCH}${XB_VERSION_EXTRA}"
storage/innobase/xtrabackup/utils/percona-xtrabackup.spec:4:%define xb_version_extra @@XB_VERSION_EXTRA@@
storage/innobase/xtrabackup/utils/build-dpkg.sh:48:XTRABACKUP_VERSION="${XB_VERSION_MAJOR}.${XB_VERSION_MINOR}.${XB_VERSION_PATCH}${XB_VERSION_EXTRA}"
XB_VERSION:4:XB_VERSION_EXTRA=
[openxs@chief percona-xtrabackup-2.2]$

We can clearly see that extra dot for RPM_EXTRAVER.