version string: use pure git commit only am: 6bca1bdb79 am: 0418a07325 am: 18a52e8b48

Original change: https://android-review.googlesource.com/c/platform/external/libabigail/+/1664042

Change-Id: I307383848f518ce2e353d2b1cde7d3b140090150
diff --git a/android_build_version.sh b/android_build_version.sh
index b6ff238..c477ffd 100755
--- a/android_build_version.sh
+++ b/android_build_version.sh
@@ -6,6 +6,6 @@
 dir="$1"
 out="$2"
 
-version=$(git -C "$dir" describe --abbrev=8 --always)-soong
+version=$(git -C "$dir" rev-parse --short=8 HEAD)-soong
 
 echo "#define ANDROID_BUILD_VERSION \"${version}\"" > "$out"