audit: check test system calls are fully scoped.

audit: check for master branch tar/zipballs.

superenv: treat timingsafe_bcmp as weak on 10.11

Revert "audit: check the version does not decrease."

Move `test/vendor/bundle` to `vendor/bundle`.

This doesn't matter for everything but it does for the binaries that
are installed. Have a limited name/alias check when not installed and
a better one that iterates bin/sbin if installed.

These have unstable checksums and aren't the tagged, stable releases
we require.

audit: check the version does not decrease.

update-test: fix --to-tag failure on new tag.

hbc/auditor: refactor and fix bug

Without this updating to a tag will always have the same start commit
and end commit as there's been no updates to `master` since the tag was
created.

Xcode 8.1 added timingsafe_bcmp to string.h and libsystem_c.tbd,
and 10.12.1 added it to libsystem_c.dylib, but it is not present in
libsystem_c.dylib on 10.11.6 (15G1108).

It may appear in libsystem_c.dylib in a later 10.11 release or it may
be marked weak on 10.11 in a later Xcode release.

Fixes Homebrew/homebrew-core#6344.

docs: remove zmwangx from the list of maintainers

XCode 8.1 is stable

Redirect stderr output from git (shim) invocations to /dev/null.

These invocations occur before we can actually automatically install git via
bottle, and as such their output isn't relevant.

audit: check for alpha/beta/rc usage in URLs.

bottle: fix nonexistent pyc bug

formula_installer: fix regression in #1253

Fix cask's restarting incomplete downloads

Open the incomplete download in append mode instead of write mode.
Opening in write mode truncates the existing file, so curl keeps
restarting downloads instead of resuming the incomplete downloads.

Apparently `cellar :any_skip_relocation` doesn't actually mean we
can skip relocation, at least for text files.

We were deleting pyc files *after* replace_locations_with_placeholders
and recording changed_files, meaning that some of the recorded files
were to be deleted. The correct order is the opposite.

A sample failed session: https://bot.brew.sh/job/Homebrew%20Core/10080/version=el_capitan/testReport/junit/brew-test-bot/el_capitan/bottle_buku/.

keg_relocate: cache files rewritten during brew bottle

Replace relocate_text_files with three methods that clarify intent:
replace_locations_with_placeholders, replace_placeholders_with_locations
and replace_text_in_files, the first two calling the third.

`brew bottle` replaces instances of the Homebrew prefix, cellar, and
repository with placeholders in all text files. Cache these files in
INSTALL_RECEIPT.json so that we don't have to check every single text
file for placeholders on install.

Move cask's fixtures to `test/fixtures`.

Don’t use bare percent literals.