Reduce memory usage for uploading

A per instance copy of data was kept in scope throughout download
process.  Minimize that to once regardless of instances, and have
lifetime of the extra copy be very short.

Change-Id: Ife3c7f83bf9b97925cf079597f014db648b227ba

pyghmi/ipmi/oem/lenovo/imm.py

@@ -279,7 +279,10 @@ class IMMClient(object):
 
     def weblogout(self):
         if self._wc:
-            self._wc.grab_json_response(self.logouturl)
+            try:
+                self._wc.grab_json_response(self.logouturl)
+            except Exception:
+                pass
             self._wc = None
 
     def hardware_inventory_map(self):
@@ -531,6 +534,7 @@ class XCCClient(IMMClient):
             self.wc.set_header('X-XSRF-TOKEN', self.wc.cookies['_csrf_token'])
 
     def update_firmware_backend(self, filename, data=None, progress=None):
+        self.weblogout()
         self._refresh_token()
         rsv = self.wc.grab_json_response('/api/providers/fwupdate', json.dumps(
             {'UPD_WebReserve': 1}))

pyghmi/util/webclient.py

@@ -43,6 +43,8 @@ def get_upload_form(filename, data):
     try:
         return uploadforms[filename]
     except KeyError:
+        if isinstance(data, file):
+            data = data.read()
         form = '--' + BND + '\r\nContent-Disposition: form-data; ' \
                             'name="{0}"; filename="{0}"\r\n'.format(filename)
         form += 'Content-Type: application/octet-stream\r\n\r\n' + data
@@ -118,8 +120,6 @@ class SecureHTTPConnection(httplib.HTTPConnection, object):
         """
         if data is None:
             data = open(filename, 'rb')
-        if isinstance(data, file):
-            data = data.read()
         form = get_upload_form(filename, data)
         ulheaders = self.stdheaders.copy()
         ulheaders['Content-Type'] = 'multipart/form-data; boundary=' + BND