Make Bazel not crash if a runfiles tree is in a runfiles tree.

There was a test for this, but it didn't check for the exit code, only the error message and the message printed on the crash coincidentally contained the expected message.

My best understanding is that this was broken in unknown commit. The root cause of why that change was imperfect is probably the odd behavior that if one posts an error to the event handler in ActionExecutionContext, the action doesn't automatically fail.

RELNOTES: None.
(cherry picked from commit ebced66)

third_party/bazel/src/main/protobuf/failure_details.proto

@@ -1256,6 +1256,7 @@ message Analysis {
     INCOMPATIBLE_TARGET_REQUESTED = 19 [(metadata) = { exit_code: 1 }];
     ANALYSIS_FAILURE_PROPAGATION_FAILED = 20 [(metadata) = { exit_code: 1 }];
     ANALYSIS_CACHE_DISCARDED = 21 [(metadata) = { exit_code: 1 }];
+    INVALID_RUNFILES_TREE = 22 [(metadata) = { exit_code: 1 }];
   }
 
   Code code = 1;