virtual_sdcard: Don't wait for M25 in an SD gcode file

If an M25 is in a gcode file that is being printed from virtual SD, it
would cause a permanent hang.  Detect that case and don't wait for
those M25 commands.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

klippy/extras/virtual_sdcard.py

@@ -16,7 +16,7 @@ def __init__(self, config):
         self.file_position = self.file_size = 0
         # Work timer
         self.reactor = printer.get_reactor()
-        self.must_pause_work = False
+        self.must_pause_work = self.cmd_from_sd = False
         self.work_timer = None
         # Register commands
         self.gcode = printer.lookup_object('gcode')
@@ -64,7 +64,7 @@ def is_active(self):
     def do_pause(self):
         if self.work_timer is not None:
             self.must_pause_work = True
-            while self.work_timer is not None:
+            while self.work_timer is not None and not self.cmd_from_sd:
                 self.reactor.pause(self.reactor.monotonic() + .001)
     # G-Code commands
     def cmd_error(self, params):
@@ -177,16 +177,19 @@ def work_handler(self, eventtime):
                 self.reactor.pause(self.reactor.monotonic() + 0.100)
                 continue
             # Dispatch command
+            self.cmd_from_sd = True
             try:
                 self.gcode.run_script(lines[-1])
             except self.gcode.error as e:
                 break
             except:
                 logging.exception("virtual_sdcard dispatch")
                 break
+            self.cmd_from_sd = False
             self.file_position += len(lines.pop()) + 1
         logging.info("Exiting SD card print (position %d)", self.file_position)
         self.work_timer = None
+        self.cmd_from_sd = False
         return self.reactor.NEVER
 
 def load_config(config):