timezone selector in workout edit form

rowers/models.py

@@ -1810,6 +1810,11 @@ class WorkoutForm(ModelForm):
         self.fields['private'] = forms.BooleanField(initial=False,
                                                     required=False,
                                                     label='Private')
+        
+        self.fields['timezone'] = forms.ChoiceField(
+            choices = [(x,x) for x in pytz.common_timezones]
+            )
+        
         if 'instance' in kwargs:
             if kwargs['instance'].privacy == 'visible':
                 self.fields['private'].initial = False

rowers/views.py

@@ -6,6 +6,7 @@ import zipfile
 import bleach
 import arrow
 import pytz
+from pytz import UnknownTimeZoneError
 import operator
 import warnings
 import urllib
@@ -9333,17 +9334,23 @@ def workout_edit_view(request,id=0,message="",successmessage=""):
                 date,starttime
                 )
 
-            startdatetime = pytz.timezone(thetimezone).localize(
-                startdatetime
+            try:
+                startdatetime = pytz.timezone(thetimezone).localize(
+                    startdatetime
                 )
+            except UnknownTimeZoneError:
+                pass
 
             try:
                 # aware object can be in any timezone
                 out = startdatetime.astimezone(pytz.utc)
             except (ValueError, TypeError):
 	        startdatetime = timezone.make_aware(startdatetime)
-                
-            startdatetime = startdatetime.astimezone(pytz.timezone(thetimezone))
+
+            try:
+                startdatetime = startdatetime.astimezone(pytz.timezone(thetimezone))
+            except UnknownTimeZoneError:
+                thetimezone = 'UTC'
 
 
             # check if user is owner of this workout