README: add moisan to maintainers.

utils/github: add ValidationFailedError.

These have specific errors returned so would be more useful to output.

Fix cleanup of incomplete downloads.

bottles: make `or_later` the default.

analytics: fix display of build error options.

Shorten tap line length

Generate Cobertura coverage data for Azure Pipelines

These can be used and displayed directly in the Azure Pipelines GUI.

It may not end up replacing CodeCov but it's easy enough so: why not.

cli_parser: improve help text formatting

Currently these are all like `wget #<Options:0x0000000101171658>`.

Cask: fix quarantine check when xattr is broken 

Cask: set write permissions on symlinks

Use the `all` matcher to check the existence of each path.

When Mojave was in beta we made it so that High Sierra bottles would
automatically be used on Mojave. Let's make this the default in general:
older bottles will be used on newer versions of macOS when a newer
bottle is not available.

This should make it easier for taps to bottle single versions of bottles
which will work more widely and to give us breathing room whenever a new
version of macOS is released.

Currently this only applies to the `wine` formula which will have the
`or_later` removed in a Homebrew/homebrew-core PR.

Question: should we use an `odeprecated` for the use of `or_later`?

Bump mustache from 1.0.5 to 1.1.0 in /Library/Homebrew/test

Use cache_store for descriptions

This makes use of both the existing interfaces and could use the
existing cache file but we'll create a new one and cleanup the old one
to avoid issues and use a more consistent name.

This change allows us to remove the `RSpec/IteratedExpectation` rule from `.rubocop_todo.yml` as we no longer iterate over each path to check existence.

Note: We this PR didn't change the subsequent test checking for the negative expectations as this isn't part of the rule (see: https://github.com/rubocop-hq/rubocop-rspec/issues/278).

Bumps [mustache](https://github.com/mustache/mustache) from 1.0.5 to 1.1.0.
- [Release notes](https://github.com/mustache/mustache/releases)
- [Changelog](https://github.com/mustache/mustache/blob/master/HISTORY.md)
- [Commits](https://github.com/mustache/mustache/compare/v1.0.5...v1.1.0

)

Signed-off-by: dependabot[bot] <support@dependabot.com>

- reduce desc_line_length so `brew help` output fits in 80 columns
- support special formatting across line breaks
- support emphasis using asterisks
- add missing depends_on: tests

bump-formula-pr: gracefully handle unforkable repositories

rubocop: only use config if style is testing specified file(s)

azure/travis: update to xcode 10

audit: use `core_tap` instead of `official_tap`

Bump octokit from 4.12.0 to 4.13.0 in /docs

Bumps [octokit](https://github.com/octokit/octokit.rb) from 4.12.0 to 4.13.0.
- [Release notes](https://github.com/octokit/octokit.rb/releases)
- [Changelog](https://github.com/octokit/octokit.rb/blob/master/RELEASE.md)
- [Commits](https://github.com/octokit/octokit.rb/compare/v4.12.0...v4.13.0

)

Signed-off-by: dependabot[bot] <support@dependabot.com>

This saves an API call, and is more accurate, because the repo API
doesn't actually say whether forking is enabled, but this error message
does.

To do this, the original GitHub error message had to be accessible on
the GitHub exceptions.

GitHub seems to be discouraging forking private repositories[0]:

> By default, new organizations are configured to disallow the forking
> of private repositories.

bump-formula-pr tries to create its pull requests from a fork, so it
can't be used for private taps set up in this way.

I've added a --no-fork option that will create PRs in the tap repo
itself, rather than in a fork, to accommodate this use case.

[0]: https://help.github.com/articles/allowing-people-to-fork-private-repositories-in-your-organization/

Remove redundant check in formula_files and cask_files