Description of problem:
For software translation, the msgctxt in po files will be wiped out when pulling from zanata server.

Version-Release number of selected component (if applicable):
Server: Zanata version 1.3 (20110509-2113)
Client: zanata python client 1.3.0

How reproducible:
Always

Steps to Reproduce:
ibus-chewing has msgctxt
1. git clone git://github.com/definite/ibus-chewing.git
2. cd ibus-chewing; cmake .; make
3. Assume that ~/.config/zanata.ini contain correct server and user information
4. Assume zanata contains the project ibus-chewing and correct version.
5. zanata push --srcdir=po --transdir=po --push-trans --project-type=gettext
6. zanata pull --srcdir=po --transdir=po --push-trans
7. git diff
  
Actual results:
git diff shows that msgctxt lines are removed.

Expected results:
msgctxt lines are preserved.

Additional info: