fix(agent.host): Missing spans when handling forked processes.

In multithreaded applications (services), only the first or master
process is announced to the Agent when the service starts, but if a
not announced forked process handles the (HTTP) ENTRY requests and it
contains one or more EXIT spans created during the first request,
those EXIT spans are missed and not reported.

This fix returns True when agent.host.can_send() method is called and
detected that the current process is a forked (and not yet announced).
All EXIT spans will not be discarded before announcing the forked
process to the Agent.

Signed-off-by: Paulo Vital <paulo.vital@ibm.com>

instana/agent/host.py

@@ -115,7 +115,7 @@ def can_send(self):
             self._boot_pid = current_pid
             logger.debug("Fork detected; Handling like a pro...")
             self.handle_fork()
-            return False
+            return True
 
         if self.machine.fsm.current in ["wait4init", "good2go"]:
             return True