calcs/hazard/general:

Solved a subtle bug where `parsed_source` records are duplicated if
an input model is reused. This results in a "leak" of sorts in the
number of overall tasks.

See https://bugs.launchpad.net/openquake/+bug/1098154.
tests/utils/helpers:

Added the `force_inputs` option to `run_risk_job_sp` and `run_hazard_job_sp`
so that users of these util functions specify whether `--force-inputs` is on
or off.
tests/calcs/hazard/general_test:

Added a test specifically for
https://bugs.launchpad.net/openquake/+bug/1098154.

If this test is run without the fix (see commit
434451cbd52901cdc601f953281f09f0ae2247e6), it will fail.
calcs/hazard/general:

PEP8 fixes; there were two new lines of excessive length.
Merge pull request #997 from larsbutler/task-count-bugfix

Fix for bug # 1098154

[r=micheles] [f=1098154]