GSM: Add an ensure block to always signal when we leave here

GSMDriver.st

@@ -60,6 +60,7 @@ classes.'>
         "Process all messages in a thread"
 
         proc := [
+                [
                 [
                     [true] whileTrue: [
                         | msg |
@@ -67,6 +68,9 @@ classes.'>
                         self dispatch: msg.
                     ].
                 ] on: SystemExceptions.EndOfStream do: [
+                    'Server is disconnected' printNl.
+                ].
+                ] ensure: [
                     completeSem signal.
                 ].
         ] fork.