Fixed #9589 -- Made development web server more robust in the presence of a wider variety of code errors.

Thanks goes to contributor with Trac user 'berto' for the patch.

AUTHORS

@@ -91,6 +91,7 @@ answer newbie questions, and generally made Django that much better:
     James Bennett
     Danilo Bargen
     Shai Berger <shai@platonix.com>
+    berto
     Julian Bez
     Arvis Bickovskis <viestards.lists@gmail.com>
     Natalia Bidart <nataliabidart@gmail.com>

django/utils/autoreload.py

@@ -28,7 +28,7 @@
 # OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-import os, sys, time, signal
+import os, sys, time, signal, traceback
 
 try:
     from django.utils.six.moves import _thread as thread
@@ -52,10 +52,12 @@ RUN_RELOADER = True
 _mtimes = {}
 _win = (sys.platform == "win32")
 
+_error_files = []
+
 def code_changed():
     global _mtimes, _win
     filenames = [getattr(m, "__file__", None) for m in sys.modules.values()]
-    for filename in filter(None, filenames):
+    for filename in filter(None, filenames) + _error_files:
         if filename.endswith(".pyc") or filename.endswith(".pyo"):
             filename = filename[:-1]
         if filename.endswith("$py.class"):
@@ -71,9 +73,34 @@ def code_changed():
             continue
         if mtime != _mtimes[filename]:
             _mtimes = {}
+            try:
+                del _error_files[_error_files.index(filename)]
+            except ValueError:
+                pass
             return True
     return False
 
+def check_errors(fn):
+    def wrapper(*args, **kwargs):
+        try:
+            fn(*args, **kwargs)
+        except (ImportError, IndentationError, NameError, SyntaxError,
+                TypeError, AttributeError):
+            et, ev, tb = sys.exc_info()
+
+            if getattr(ev, 'filename', None) is None:
+                # get the filename from the last item in the stack
+                filename = traceback.extract_tb(tb)[-1][0]
+            else:
+                filename = ev.filename
+
+            if filename not in _error_files:
+                _error_files.append(filename)
+
+            raise
+
+    return wrapper
+
 def ensure_echo_on():
     if termios:
         fd = sys.stdin
@@ -142,5 +169,7 @@ def main(main_func, args=None, kwargs=None):
         reloader = jython_reloader
     else:
         reloader = python_reloader
-    reloader(main_func, args, kwargs)
+
+    wrapped_main_func = check_errors(main_func)
+    reloader(wrapped_main_func, args, kwargs)