Recognizing Launcher builds consisting only of digits

Bug: 206687633
Test: online regex tools
Change-Id: Ia6155f22fb9a0eba3beb6edb607f44f901629330
diff --git a/tests/src/com/android/launcher3/util/rule/TestStabilityRule.java b/tests/src/com/android/launcher3/util/rule/TestStabilityRule.java
index de36d5f..f33a50a 100644
--- a/tests/src/com/android/launcher3/util/rule/TestStabilityRule.java
+++ b/tests/src/com/android/launcher3/util/rule/TestStabilityRule.java
@@ -41,7 +41,7 @@
             Pattern.compile("^("
                     + "(?<local>(BuildFromAndroidStudio|"
                     + "([0-9]+|[A-Z])-eng\\.[a-z]+\\.[0-9]+\\.[0-9]+))|"
-                    + "(?<platform>[A-Z]([a-z]|[0-9])*)"
+                    + "(?<platform>([A-Z][a-z]*[0-9]*|[0-9]+)*)"
                     + ")$");
     private static final Pattern PLATFORM_BUILD =
             Pattern.compile("^("