I'm not sure if this is some kind of bug (probably not, otherwise everyone would complain) and without a google account, I can't use the google group, so I try my luck here in the hope that somebody has a suggestion.
I have YouCompleteMe installed with clang-completer and stuff works fine for C, C++. Now I edit a .py file, and the only completions offered are the words already in the buffer. No semantic completion. :YcmCompleter prints No semantic completer exists for filetypes: [u'py']. I have removed everything except the following from my .vimrc:
call pathogen#infect()
Helptags
filetype on
To no avail. Does anybody have an idea how to better diagnose the problem?
Edit: I realised I did not have jedi installed. So I ran pip install jedi which strangely changed nothing.
It turns out hat I had an ftplugin for .py files which would set the filetype to py instead of python as is intended. Disabling it solved the issue.