Revert "Run unit tests on all cros-workon packages in full builders."

This reverts commit a5d812e827d5f9fe1d625095e0ba7806d6641b0f.

The reverted CL introduced unit-test failures in cros-devutils and chromite:

http://build.chromium.org/p/chromiumos/builders/x86%20generic%20full/builds/8016/steps/UnitTest/logs/stdio
https://uberchromegw.corp.google.com/i/chromeos/builders/lumpy%20canary/builds/2248/steps/UnitTest/logs/stdio

Change-Id: Ib7713c900007668bb6b393cd49039fc3c7a68af0
Reviewed-on: https://gerrit.chromium.org/gerrit/43606
Reviewed-by: David James <davidjames@chromium.org>
Commit-Queue: Elly Jones <ellyjones@chromium.org>
Tested-by: Elly Jones <ellyjones@chromium.org>
diff --git a/cros_run_unit_tests b/cros_run_unit_tests
index 7b5c12b..6716ff9 100755
--- a/cros_run_unit_tests
+++ b/cros_run_unit_tests
@@ -66,10 +66,9 @@
 
 # If we didn't specify packages, find all packages.
 if [ -z "${FLAGS_package_file}" -a -z "${FLAGS_packages}" ]; then
-  PACKAGE_LIST=$( cd /usr/local/portage/chromiumos;
-                  git grep -lE '^[[:space:]]*inherit.*\<cros-workon\>' | \
-                  xargs git grep -lE '^src_test()' | \
-                  xargs -n 1 dirname | grep '/' | sort -u )
+  PACKAGE_LIST=$( /usr/lib/crosutils/get_package_list chromeos \
+                    --board="${FLAGS_board}" |
+                      egrep '^chromeos-base' )
 fi
 
 BLACK_LIST_FILE="/usr/share/crostestutils/unit_test_black_list.txt"
@@ -88,9 +87,9 @@
     warn "${package} not found"
   if [ -n "${EBUILD_PATH}" ]; then
     if check_src_test "${EBUILD_PATH}"; then
-      TEST_PACKAGE_LIST+=" ${package}"
+      TEST_PACKAGE_LIST="${TEST_PACKAGE_LIST} ${package}"
     else
-      NO_UNITTESTS+=" ${package}"
+      NO_UNITTESTS="${NO_UNITTESTS} ${package}"
     fi
   fi
 done