[rust][3p] Allow the script to continue if no OWNERS files were saved to /tmp.

Fixed: 74284
Change-Id: I163eb657e1460a40f9f2966fc535d956b3389c10
Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/514601
Fuchsia-Auto-Submit: Adam Perry <adamperry@google.com>
Reviewed-by: Claudio Cherubino <ccherubino@google.com>
Reviewed-by: Tyler Mandry <tmandry@google.com>
Commit-Queue: Auto-Submit <auto-submit@fuchsia-infra.iam.gserviceaccount.com>
diff --git a/tools/devshell/contrib/update-rustc-third-party b/tools/devshell/contrib/update-rustc-third-party
index 7692ec0..2507960 100755
--- a/tools/devshell/contrib/update-rustc-third-party
+++ b/tools/devshell/contrib/update-rustc-third-party
@@ -69,7 +69,11 @@
   -q)
 
 # restore OWNERS files
-cp -r $OWNERS_TMP/* $VENDOR_DIR/
+shopt -s nullglob
+for f in $OWNERS_TMP/*
+do
+  cp -r $f $VENDOR_DIR/
+done
 
 # restore LICENSE* files
 $FUCHSIA_DIR/scripts/rust/check_rust_licenses.py \