source/install_source.rst: pip plugin depends on host pip

See merge request !791

The first badge will work fine right away while the second badge will
show "not found" until a release is made after merging this branch:
!718.

README.rst: Add status badges for PyPI release and Python versions

See merge request !719

richardmaw-codethink authored Sep 05, 2018 and richardmaw-codethink committed Sep 13, 2018

This can get out of sync with other two cache states,
and we can do without it.

Simplify element state by removing `__cached`

See merge request !784

We can't include a socket in a CAS tree, but it's mostly meaningless to do so
since there can't possibly be a process serving it.

Fix: While caching build artifact: "Cannot extract [path to socket file] into staging-area. Unsupported type."

See merge request !783

richardmaw-codethink authored Sep 10, 2018 and richardmaw-codethink committed Sep 14, 2018

Since we now set PWD in the environment of builds
existing builds may behave differently so must cache differently now.

richardmaw-codethink authored Sep 11, 2018 and richardmaw-codethink committed Sep 14, 2018

The current directory isn't always in the python module search path,
so we have to ensure it is for the script to work.

Strictly speaking, the user may already have a modified PYTHONPATH
at which point PYTHONPATH=".${PYTHONPATH+:$PYTHONPATH}" is necessary,
but it's probably premature to overcomplicate the documentation like that
before we discover it's a problem.