[eclass, *] sab-patches.eclass: don't change SRC_URI uncontrolled

dev-vcs/git-subversion/git-subversion-2.3.2.ebuild

@@ -26,7 +26,7 @@ if [[ ${PV} != *9999 ]]; then
 	SRC_URI_SUFFIX="xz"
 	SRC_URI_GOOG="http://git-core.googlecode.com/files"
 	SRC_URI_KORG="mirror://kernel/software/scm/git"
-	SRC_URI+=" ${SRC_URI_GOOG}/${MY_P}.tar.${SRC_URI_SUFFIX}
+	SRC_URI="${SRC_URI_GOOG}/${MY_P}.tar.${SRC_URI_SUFFIX}
 			${SRC_URI_KORG}/${MY_P}.tar.${SRC_URI_SUFFIX}
 			${SRC_URI_GOOG}/${MY_PN}-manpages-${DOC_VER}.tar.${SRC_URI_SUFFIX}
 			${SRC_URI_KORG}/${MY_PN}-manpages-${DOC_VER}.tar.${SRC_URI_SUFFIX}
@@ -37,6 +37,8 @@ if [[ ${PV} != *9999 ]]; then
 	KEYWORDS="~amd64 ~x86"
 fi
 
+sab-patches_update_SRC_URI
+
 LICENSE="GPL-2"
 SLOT="0"
 IUSE="doc iconv nls +threads"