In TestInfoDecorator, only reraise a caught Exception as TestError if it isn't already a TestSignal.

Bug: 147562682
Test: local
Change-Id: Iaad219cf0c5f01f2380847092e794befc3f8d19c
diff --git a/acts/framework/acts/test_decorators.py b/acts/framework/acts/test_decorators.py
index 624683f..e1cd37f 100644
--- a/acts/framework/acts/test_decorators.py
+++ b/acts/framework/acts/test_decorators.py
@@ -95,6 +95,8 @@
                 new_signal = signals.TestPass('')
             else:
                 new_signal = signals.TestFailure('')
+        except signals.TestSignal as signal:
+            new_signal = signal
         except Exception as cause:
             new_signal = signals.TestError(cause)