Closes #181.

Signed-off-by: Xu Cheng <xucheng@me.com>

a Bash implementation of lock using `flock(2)`.

The fix changes behavior in same cases, but those cases were all either
broken or showed unexpected behavior. The new behavior is very simple:

- If an argument starts with `--<option-name>=`, return whatever comes
  after the equals sign.

Prior to this change, `ARGV.value` showed some unexpected behavior:

- `ARGV.value("foo")` returned `nil` for `--foo=` because at least one
  character needed to be present after the equals sign. (All other
  option parser implementations I'm aware of allow for empty values.)

- `ARGV.value("bar")` returned `"baz"` for `--foo=--bar=baz` because the
  regular expression was not anchored to the start of the argument.

- `ARGV.value("++")` raised an exception because the string wasn't
  escaped for use in the regular expression. (An unlikely corner case.)

Closes #231.

Signed-off-by: Martin Afanasjew <martin@afanasjew.de>

When passing formula options with value, e.g. `--with-qt=5`, to the
child process responsible for building a formula, `ARGV.value` would be
invoked with `nil`. Handle this more elegantly (no change in behavior).

For consistency, use a regular expression adapted from `Options.create`
instead of the somewhat bogus one used before.

I'm not completely sure this is "sane" logic but I'm leery of just reverting
Andrew's work this morning and making him rebuild that PR from scratch for one
syntax issue.

Sadly, because we run:
```
brew readall --aliases --syntax
```
On every CI job, and that flags this line previously as:
```
pull.rb:555: warning: possibly useless use of a variable in void context
```

Every single PR has "failed" since it was merged, and it's reached the point
of being a bit annoying, so let's try this.

Works around issue with GET and HEAD apparently acting differently, and
bottle downloads failing even after successful polling completion.

Closes #1028.

Fix regression introduced in fafe8f0f.
Counting the number of hyphens in a string cannot be done in a single
expression, thus split this and introduce another local variable.

Fixes #227.

Fix regression introduced in fafe8f0f.

CPU was transformed into a class in 8d995e96.

Seems like last-minute changes were made without re-running `brew man`.

The previous fixes in c6dc50fc and
ed9f7308 were incomplete as they
referenced `DeveloperTools`, but the actual name is `DevelopmentTools`.

Also fixes indentation and a broken `MacOS.clang_version` (it was
falsely redirecting to `DeveloperTools.llvm_build_version` ).

References #219.
References #220.

Closes #220.

Follow-up to c7edf9a0 and related to
changes from #168.

Closes #219.

Make sure `Regexp.escape` gets a string as Ruby 1.8 is unable to convert
the symbol to a string automatically. Related to changes from #168.

Partially addresses #219. Related to changes introduced in #168.

Closes #216.

Makes it easy to debug what’s gone wrong.

Makes it easier to quickly do tests of the generic/cross-platform
backend.

Closes #216.

Closes #214.
Closes #215.

Closes #168.

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>

If the environment variable HOMEBREW_TEST_GENERIC_OS is set ensure that
neither Mac nor Linux-specific code is loaded. This allows easier
testing of cross-platform code on OS X and will make it easier to port
Homebrew to platforms other than OS X and Linux.

This is in part designed to handle situations described in https://github.com/Homebrew/legacy-homebrew/issues/42273
where we tell someone to install a special dependency, but because we (rightly, IMO)
resolve special dependencies first users can end up being told to execute a command
on a tool that isn't yet installed and isn't immediately obvious how to install it.

In the situation raised there, with the `sile` formula people are being told to
`luarocks install xyz` but we hadn't installed Lua for them first, so they just
get a `command not found: luarocks` message. Perhaps it should be obvious enough
how to install said tools by looking at the formula's dependencies,
but it's not a huge burden on us to make life easier than that.

Shuffled over from https://github.com/Homebrew/legacy-homebrew/pull/42576.