Fix racing-condition for files coming in after post-proc is started

Files could still come in after post-proc is already started. Post-proc could even have already deleted the job folder, resulting in Assembler errors for these new files. So when post-proc is active, it is safe to ignore write-errors.
Linked topic: https://forums.sabnzbd.org/viewtopic.php?f=3&t=23049

sabnzbd/assembler.py

@@ -97,8 +97,8 @@ class Assembler(Thread):
                     try:
                         filepath = self.assemble(nzf, filepath)
                     except IOError, (errno, strerror):
-                        # If job was deleted, ignore error
-                        if not nzo.is_gone():
+                        # If job was deleted or in active post-processing, ignore error
+                        if not nzo.is_gone() and not nzo.pp_active:
                             # 28 == disk full => pause downloader
                             if errno == 28:
                                 logging.error(T('Disk full! Forcing Pause'))

sabnzbd/postproc.py

@@ -219,6 +219,9 @@ class PostProcessor(Thread):
                 history_db.close()
                 nzo.purge_data(keep_basic=False, del_files=True)
 
+            # Processing done
+            nzo.pp_active = False
+
             self.remove(nzo)
             check_eoq = True