try/except around get_file_type to catch corrupt gzip

rowers/dataprep.py

@@ -828,7 +828,13 @@ def new_workout_from_file(r,f2,
                           makeprivate=False,
                           notes=''):
     message = None
-    fileformat = get_file_type(f2)
+    try:
+        fileformat = get_file_type(f2)
+    except IOError:
+        os.remove(f2)
+        message = "Rowsandall could not process this file. The extension is supported but the file seems corrupt. Contact info@rowsandall.com if you think this is incorrect."
+        return (0,message,f2)
+        
     summary = ''
     oarlength = 2.89
     inboard = 0.88