ansible: clean up formula, fix system Python use.

Closes #22307.
mongodb: fix config file installation.

References #22149.
Closes #22329.
Closes #22331.
Make reinstall transaction safe.

* Aborting during reinstall will now restore the originally installed
  keg.
  - Change install code to pass on CannotInstallFormulaError exception
    to caller so it can be reused in reinstall.
* Add "--force-new-install" flag to force installing a new formula.

Closes #22190.

Signed-off-by: Samuel John <github@SamuelJohn.de>
reinstall cleanup
Improve python tests for brew bots

Allow `build.with?` and similar methods to be used during the test
phase. The BuildOptions (`build`) are initialized with the
`Tab.used_options` unless explicitly overwritten on the command line.

So basically `build.with?` works in `def install` and in `test do` as
one would naively expect. (For the test, gramatically it should be
`built.with?` but who cares)

If a formula was installed `--with-python`, now the tests are also
run `--with-python`. This enables us to use the `python do ... end` in
a meaningful manner.

Using `python do ... end` blocks for the tests, because the bot.brew.sh has
system python per default and we need to set the PYTHONPATH for the test.
Potentially to different values for Python 2.x and 3.x.
mongodb: create var directories in post_install.
elixir: use a requirement with a default formula for erlang
postgres usage in caveats; Closes #21920

As a PostgreSQL n00b, this is the information I wanted.

Ideally we’d set a default configuration location for postgres to look, however apparently, this is not possible.

Side note: it's about time we split caveats out. One of these is advise for failed builds, and I just added usage. Usage is hardly caveats, but generally usage is cool and we should encourage it as a separate section, and encourage people to add links perhaps.
sshuttle: fix checksum

Closes #22334.

Signed-off-by: Jack Nagel <jacknagel@gmail.com>
tinc 1.0.22

Updated tinc to 1.0.22

Closes #22330.

Signed-off-by: Jack Nagel <jacknagel@gmail.com>
node devel 0.11.7

Closes #22322.

Signed-off-by: Jack Nagel <jacknagel@gmail.com>
unrar 5.0.11

Closes #22326.

Signed-off-by: Jack Nagel <jacknagel@gmail.com>
Suggest installing pip via easy_install
node 0.10.18

Closes #22316.

Signed-off-by: Jack Nagel <jacknagel@gmail.com>
node: fix compilation on 10.6
homebank 4.5.2

Closes #22341.

Signed-off-by: Jack Nagel <jacknagel@gmail.com>
the_silver_searcher: install bash-completion script

Closes #22306.

Signed-off-by: Jack Nagel <jacknagel@gmail.com>
pyqt5 5.0.1

Closes #22340.

Signed-off-by: Jack Nagel <jacknagel@gmail.com>