if the debian package name for 5.5.28 is 5.5.28-mariadb1~wheezy

then for 5.5.28a it should be
5.5.28a-mariadb1~wheezy not 5.5.28-mariadb-a1~wheezy

debian/autobake-deb.sh

@@ -18,8 +18,8 @@ export DEB_BUILD_OPTIONS="nocheck"
 # Find major.minor version.
 #
 source ./VERSION
-UPSTREAM="${MYSQL_VERSION_MAJOR}.${MYSQL_VERSION_MINOR}.${MYSQL_VERSION_PATCH}"
-RELEASE_EXTRA=${MYSQL_VERSION_EXTRA}
+UPSTREAM="${MYSQL_VERSION_MAJOR}.${MYSQL_VERSION_MINOR}.${MYSQL_VERSION_PATCH}${MYSQL_VERSION_EXTRA}"
+RELEASE_EXTRA=""
 
 RELEASE_NAME=mariadb
 PATCHLEVEL=""