chroot_version_hooks.d: ignore pypy3 unmerge failures

If the package isn't installed, there's nothing to do.

BUG=b:207726852
TEST=CQ passes

Change-Id: Iaf62d1878f8e2bbef3b412e345a23709f2adf4f5
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosutils/+/3301402
Tested-by: Mike Frysinger <vapier@chromium.org>
Tested-by: Fei Shao <fshao@chromium.org>
Reviewed-by: Fei Shao <fshao@chromium.org>
Reviewed-by: Grant Grundler <grundler@chromium.org>
diff --git a/chroot_version_hooks.d/189_purge_pypy b/chroot_version_hooks.d/189_purge_pypy
index 35ac2ed..127df1a 100644
--- a/chroot_version_hooks.d/189_purge_pypy
+++ b/chroot_version_hooks.d/189_purge_pypy
@@ -4,4 +4,4 @@
 
 # Force rebuild of pypy3 to ensure portage picks up changes that cause byte
 # compilation of pypy3 libs.
-sudo emerge --rage-clean pypy3
+sudo emerge --rage-clean pypy3 || :