I'm guessing the commands under ruby-core setup are very long, so the
title gets truncated. Use a shorter title, since the test doesn't really
care.

The `gem_command` helper was failing to require `support/hax.rb`, which
takes care of making sure rubygems actually picks up the right `ruby`
executable under ruby-core setup (`ENV["RUBY"]`). This caused binstubs
to be generated with a wrong shebang, and that caused `bundle exec` to
not work. The error message was pretty confusing though due to
https://bugs.ruby-lang.org/issues/16952.

Try to fix 404 error on mswinci.

https://rubyci.org/logs/mswinci.japaneast.cloudapp.azure.com/vc12-x64/ruby-master/log/20200614T225859Z.fail.html.gz
```
  1) Failure:
WEBrick::TestFileHandler#test_cjk_in_path [D:/tmp/mswin-build20200615-24932-11ykstf/ruby/test/webrick/utils.rb:72]:
exceptions on 2 threads:
webrick log start:
  [2020-06-15 09:48:29] ERROR `/あ.txt' not found.

webrick log end.
<"200"> expected but was
<"404">.
---
<[]> expected but was
<["[2020-06-15 09:48:29] ERROR `/\xE3\x81\x82.txt' not found.\n"]>.
```

failure on TestFTP.

When we skip a test, the place to hang (long wait for compilation)
just moves to another test and it doesn't seem to finish.
http://ci.rvm.jp/results/trunk-mjit-wait@silicon-docker/3003055

with Ripper.

a3e6f52c introduced __builtin_cexpr! and
__builtin_cstmt!, but nobody has used them and then they broke on
79292b30 by undefined `params`.

This patch fixes the undefined `params`, but still we're not using them
yet.

Timeout-based test often fails with --jit-wait as a false positive.
Like other tests in the TestFTP, let me skip this as well.

http://ci.rvm.jp/results/trunk-mjit-wait@silicon-docker/3001181
http://ci.rvm.jp/results/trunk-mjit-wait@silicon-docker/3000134
http://ci.rvm.jp/results/trunk-mjit-wait@silicon-docker/2999923
http://ci.rvm.jp/results/trunk-mjit-wait@silicon-docker/2998857

Methods:

    #join
    #inspect/#to_s
    #to_a

Scripts to run the interpreter via debugger.

Methods:

    #insert
    #each
    #each_index
    #reverse_each
    #length
    #empty?

The code assumed that /usr/share/dict/words did not use mixed
case, and it does at least on a few operating systems.

From CryptoRAT (Luke Elliot)

Fixes [Bug #16957]

This reverts commit 7cddb844,
because the test of rake 13.0.1 is depending on the previous
behavior.

`FileUtils#install` methed raises an unexpected `TypeError`, when
called with `mode:` option which has `"X"`.

```
$ ruby -rfileutils -e 'FileUtils.install("tmp/a", "tmp/b", mode: "o+X")'
/opt/local/lib/ruby/2.7.0/fileutils.rb:942:in `directory?': no implicit conversion of File::Stat into String (TypeError)
	from /opt/local/lib/ruby/2.7.0/fileutils.rb:942:in `block (3 levels) in symbolic_modes_to_i'
	from /opt/local/lib/ruby/2.7.0/fileutils.rb:933:in `each_char'
	from /opt/local/lib/ruby/2.7.0/fileutils.rb:933:in `each'
	from /opt/local/lib/ruby/2.7.0/fileutils.rb:933:in `inject'
	from /opt/local/lib/ruby/2.7.0/fileutils.rb:933:in `block (2 levels) in symbolic_modes_to_i'
	from /opt/local/lib/ruby/2.7.0/fileutils.rb:931:in `each'
	from /opt/local/lib/ruby/2.7.0/fileutils.rb:931:in `each_slice'
	from /opt/local/lib/ruby/2.7.0/fileutils.rb:931:in `block in symbolic_modes_to_i'
	from /opt/local/lib/ruby/2.7.0/fileutils.rb:926:in `each'
	from /opt/local/lib/ruby/2.7.0/fileutils.rb:926:in `inject'
	from /opt/local/lib/ruby/2.7.0/fileutils.rb:926:in `symbolic_modes_to_i'
	from /opt/local/lib/ruby/2.7.0/fileutils.rb:973:in `fu_mode'
	from /opt/local/lib/ruby/2.7.0/fileutils.rb:883:in `block in install'
	from /opt/local/lib/ruby/2.7.0/fileutils.rb:1588:in `block in fu_each_src_dest'
	from /opt/local/lib/ruby/2.7.0/fileutils.rb:1604:in `fu_each_src_dest0'
	from /opt/local/lib/ruby/2.7.0/fileutils.rb:1586:in `fu_each_src_dest'
	from /opt/local/lib/ruby/2.7.0/fileutils.rb:877:in `install'
	from -e:1:in `<main>'
```

In spite of that `symbolic_modes_to_i` considers the `File::Stat`
`path` case at the beginning, in `"X"` case, `path` is passed to
`FileTest.directory?` method which requires a `String`.  In such
case, the mode in `path` should be examined instead.

https://github.com/ruby/fileutils/commit/af675af6b2

Verbose output is not error output, and should be sent to
stdout and not stderr.

Fixes Ruby bug 4436

https://github.com/ruby/fileutils/commit/563a383025

We observed test failures on test_latest_gc_info with random
order CI.
http://ci.rvm.jp/results/trunk-random1@phosphorus-docker/2998078l0ll

To solve it, use a pre-allocated hash object and rehearsal.

Maybe 182ae140 missed it.

Fixes [Bug #15834]

Setting class varibles goes through the ancestor list which can
contain iclasses. Iclasses share a lot of information with the
module they are made from, but not the frozen status.

Check the frozen status of the module instead of the iclass.

* Enhanced Rdoc for Array#rindex and Array#[]=

* Enhanced Rdoc for Array#rindex and Array#[]=

Implements [Feature #15973]

Sorted the lines asnd added mjit_build_dir.o dependencies.

When `LANG=C`, dir is `UTF-8` and `base` is 'ASCII-8BIT` in `FileUtils::Entry_#join`.
So `Encoding::CompatibilityError` occurred and files are not removed.

https://rubyci.org/logs/rubyci.s3.amazonaws.com/arch/ruby-master/log/20200611T060002Z.fail.html.gz
```
  1) Error:
WEBrick::TestFileHandler#test_cjk_in_path:
Errno::ENOTEMPTY: Directory not empty @ dir_s_rmdir - /home/chkbuild/chkbuild/tmp/build/20200611T060002Z/tmp/???20200611-1887828-3nn72a
    /home/chkbuild/chkbuild/tmp/build/20200611T060002Z/ruby/lib/fileutils.rb:1460:in `rmdir'
    /home/chkbuild/chkbuild/tmp/build/20200611T060002Z/ruby/lib/fileutils.rb:1460:in `block in remove_dir1'
    /home/chkbuild/chkbuild/tmp/build/20200611T060002Z/ruby/lib/fileutils.rb:1471:in `platform_support'
    /home/chkbuild/chkbuild/tmp/build/20200611T060002Z/ruby/lib/fileutils.rb:1459:in `remove_dir1'
    /home/chkbuild/chkbuild/tmp/build/20200611T060002Z/ruby/lib/fileutils.rb:1452:in `remove'
    /home/chkbuild/chkbuild/tmp/build/20200611T060002Z/ruby/lib/fileutils.rb:780:in `block in remove_entry'
    /home/chkbuild/chkbuild/tmp/build/20200611T060002Z/ruby/lib/fileutils.rb:1509:in `ensure in postorder_traverse'
    /home/chkbuild/chkbuild/tmp/build/20200611T060002Z/ruby/lib/fileutils.rb:1509:in `postorder_traverse'
    /home/chkbuild/chkbuild/tmp/build/20200611T060002Z/ruby/lib/fileutils.rb:778:in `remove_entry'
    /home/chkbuild/chkbuild/tmp/build/20200611T060002Z/ruby/lib/tmpdir.rb:97:in `mktmpdir'
    /home/chkbuild/chkbuild/tmp/build/20200611T060002Z/ruby/test/webrick/test_filehandler.rb:292:in `test_cjk_in_path'
```

https://github.com/ruby/logger/commit/2e772770be