obsdiscovery: adopt to calling convention change
Upstream commits 71d83b315778 and abce899c985f changed the calling
convention of setdiscovery._takefullsample().
We inspect the signature of the function before calling it so
we can pass the proper arguments.
syntax: re
/figures/[^/]+\.png$
^html/
\.pyc$
~$
\.swp$
\.orig$
\.rej$
^tests/.*\.err$
^tests/easy_run.sh$
^build/
^dist/
^MANIFEST$
^docs/tutorials/.*\.rst$
\.ico$
tests/\.testtimes
^docs/training/graphs/
^docs/training/html/
^docs/training/index.html
^docs/training/graphviz-images/
^docs/training/img/
^docs/training/output/
^docs/training/pandocfilters/