fixed typo
check --db parameter for 'buildbot create-master' command

Check that database URL specified via --db parameter is valid. Print
usage error otherwise.
fix and enable empty-docstring (C0112) pylint check
buildstep.py: Add support for description{,Done}

Add support for attributes description and descriptionDone in the
BuildStep class. This means that any subclass of BuildStep will also
support these attributes as well. This was not previously the case.
buildstep.py: Remove whitespace damage
test_process_buildstep: Add test for new describe()

Add test for the new functionality of the describe() method in
buildstep.BuildStep.
test_steps_master: Update tests to work with describe()

The altered tests did not work with the new functionality of the
describe() method in buildstep.BuildStep. They explicitly looked for
the name of the BuildStep when querying the status text of a
successful BuildStep, even if said BuildStep had its description-
attributes set. This commit fixes that behavior.
Do not ignore default choices for ForceScheduler list parameters
buildstep.py & shell.py: Extract common attributes to superclass

The attributes `description`, `descriptionDone` and
`descriptionSuffix` in the class `ShellCommand` have been moved to its
superclass `BuildStep`. The test for the `describe()` method that uses
these attributes has also been updated.
json: proper path root in examples

this is needed when you map the buildbot instance for example to
http://example.com/buildbot with a reverse proxy
BaseBasicScheduler: fix typo
Merge pull request #881 from lewurm/typo

BaseBasicScheduler: fix typo
tutorial, PR #760: Add Dockerfile and documentation for Buildbot Pyflakes tutorial.
buildstep.py & shell.py: Moved descriptionSuffix logic

Moved descriptionSuffix logic from shell.ShellCommand to
buildstep.BuildStep
test_process_buildstep: Updated tests for descriptionSuffix
Merge branch 'create-master-db-arg' of git://github.com/elmirjagudin/buildbot
Merge pull request #874 from elmirjagudin/pylint-empty-docstring

fix and enable empty-docstring (C0112) pylint check
fix anomalous-backslash-in-string (W1401) pylint warning

This warning is often triggered by regular expressions, and prefixing
to the open quotation mark will make python leave any escape sequences
alone, e.g.:

 - re.compile("\w+")
 + re.compile(r"\w+")

This solution is not specific for regular expressions, it can be applied
to any string that contains backslashes that python should not interpret.

This commit also enables the warning in common/pylintrc.
locally disable pylint no-value-for-parameter check

The test
test_process_properties.TestProperties.test_setProperty_no_source
generates a pylint error. Disable that check locally.
enable no-value-for-parameter (E1120) pylint check