doc/source/install_linux_distro.rst: buildstream doesn't hard depend on ostree or pygobject anymore

Closes #492

See merge request !558

This addresses issue #501.

Remove misleading info message

See merge request !567

Add test to ensure gracefull handling of exception thrown while loading
a pipeline due the python's max recursion depth being exceeded.

This is part of the work for issue #203

Because the RecursionError exception was introduced in Python 3.5, until we
drop support for for Python 3.4, we must use RuntimeError.

Phil/203 BuildStream crashes when dependency tree too deep

See merge request !512

tests/frontend/workspace.py: Added tests

_stream.py: Added functionality for workspace open -f

See merge request !549

Add a plugin that supports downloading files verbatim from a source with
an optional overridable filename and destination directory. Bumps bst
format version to 10.

Fixes #163

When the user provides a path for the filename parameter, provide a reason

Add remote source plugin

Closes #163

See merge request !541

William Salmon authored Jul 26, 2018 and Javier Jardón committed Jul 26, 2018

Daniel went through the Doc's etc and made a list of suggestions.
These are the result of the most easily patched suggestions and
one or two thing that I noticed as well.

Documentation typos and fixes

See merge request !569

job.py: Changes to the logic surrounding retry attempts and child process return codes
element.py, source.py: ElementError and SourceError also implement this change.

These exceptions now have an optional parameter of temporary which defaults to false. This will potentially break
backwards compatibility where exceptions were previously raised and a retry was intended.

To trigger a retry, one must now raise their SourceError or ElementError with temporary=True.

This aims to fix #397.

This follows the change in 67ecd97a05279a3b7570ad59f05bf0a5973ef04c.

This is following 5d6418a06a3a0262df5f6b9e6e1a36578515fd4a where
DownloadableFileSource was modified to raise 'temporary'
errors when relating to file downloading.

Further work needs to be done for the current grpc exceptions which are reraised.

Plugin.call() now takes fail_temporarily as an optional parameter,
when supplied it will cause subsequent failures to trigger temporary
errors as opposed to permanent errors.

This also extends Plugin.check_output() which makes use of Plugin.call()

The git plugin will now make use of the fail_temporarily parameter
to Plugin.call(), allowing failures to trigger a retry.

Temorary failures

Closes #397

See merge request !574

Since we backported the temporary/permanent failures patch for #397
into the `bst-1.2` branch, we need to adjust the since versions in master
down to 1.2.

Qinusty authored Jul 23, 2018 and Qinusty committed Jul 27, 2018

This address issue #491.

When attempting to run buildstream with a configuration specifying
a cache quota larger than your available disk space, buildstream
will alert the user and exit.

Note:
This takes into consideration your current cache usage and
therefore restricts the overall size of your artifact cache folder.