client: allow file upload size to be sent a string

... for uploads which sizes exceed the xmlrpc.client.MAXINT limit for int
values.  This change should not be backwards incompatible.  Old client
with newer hub should work seamlessly.  And new hub with older client
would crash with the following traceback anyway.

Fixes the following traceback:
```
$ truncate -s 2G test
$ osh/client/osh-cli mock-build --tarball-build-script=test ./test
Traceback (most recent call last):
  File "/src/osh/client/osh-cli", line 79, in <module>
    main()
  File "/src/osh/client/osh-cli", line 72, in main
    parser.run()
  File "/src/kobo/kobo/cli.py", line 296, in run
    cmd.run(*cmd_args, **cmd_kwargs)
  File "/src/osh/client/commands/cmd_diff_build.py", line 157, in run
    target_dir, self.parser)
  File "/src/osh/client/commands/shortcuts.py", line 145, in upload_file
    return hub.upload_file(os.path.expanduser(srpm), target_dir)
  File "/src/kobo/kobo/client/__init__.py", line 473, in upload_file
    upload_id, upload_key = self.upload.register_upload(os.path.basename(file_name), checksum, fsize, target_dir)
  File "/usr/lib64/python3.6/xmlrpc/client.py", line 1112, in __call__
    return self.__send(self.__name, args)
  File "/usr/lib64/python3.6/xmlrpc/client.py", line 1446, in __request
    allow_none=self.__allow_none).encode(self.__encoding, 'xmlcharrefreplace')
  File "/usr/lib64/python3.6/xmlrpc/client.py", line 971, in dumps
    data = m.dumps(params)
  File "/usr/lib64/python3.6/xmlrpc/client.py", line 502, in dumps
    dump(v, write)
  File "/usr/lib64/python3.6/xmlrpc/client.py", line 524, in __dump
    f(self, value, write)
  File "/usr/lib64/python3.6/xmlrpc/client.py", line 540, in dump_long
    raise OverflowError("int exceeds XML-RPC limits")
OverflowError: int exceeds XML-RPC limits
```

Resolves: #216

kobo/client/__init__.py

@@ -470,6 +470,10 @@ def upload_file(self, file_name, target_dir):
         checksum = sum.hexdigest().lower()
 
         fsize = os.path.getsize(file_name)
+        # use str only for large uploads to not break compatibility with older hubs
+        if fsize > xmlrpclib.MAXINT:
+            fsize = str(fsize)
+
         upload_id, upload_key = self.upload.register_upload(os.path.basename(file_name), checksum, fsize, target_dir)
 
         secure = (scheme == "https")

kobo/django/upload/xmlrpc.py

@@ -27,7 +27,8 @@ def register_upload(request, name, checksum, size, target_dir):
     upload.owner = request.user
     upload.name = name
     upload.checksum = checksum.lower()
-    upload.size = size
+    # size may be sent as a string to workaround the xmlrpc.client.MAXINT limit
+    upload.size = int(size)
     upload.target_dir = target_dir
     upload.save()
     return (upload.id, upload.upload_key)