* -Wtautological-compare

    error: self-comparison always evaluates to true [-Werror,-Wtautological-compare]
    for (win_T *wp = ((curtab) == curtab) ? firstwin : (curtab)->tp_firstwin; wp != ((void*)0); wp = wp->w_next) {

* -Wconversion

    error: implicit conversion loses floating-point precision: 'const float_T' (aka 'const double') to 'float' [-Werror,-Wconversion]
          do { const float_T flt_ = (tv->vval.v_float); switch ((sizeof (flt_) == sizeof (float) ? __fpclassifyf (flt_) : sizeof (flt_) == sizeof (double) ? __fpclassify (flt_) : __fpclassifyl (flt_))) { case 0: { ga_concat(gap, (char_u *)(char_u *) "str2float('nan')"); break; } case 1: { if (flt_ < 0) { ga_append(gap, '-'); } ga_concat(gap, (char_u *)(char_u *) "str2float('inf')"); break; } default: { char numbuf[NUMBUFLEN]; vim_snprintf(numbuf, ((sizeof(numbuf)/sizeof((numbuf)[0])) / ((size_t)(!(sizeof(numbuf) % sizeof((numbuf)[0]))))), "%g", flt_); ga_concat(gap, (char_u *)(char_u *) numbuf); } } } while (0);
                                                                                                   ~~~~~~~~~~~~~  ^~~~

After bumping Travis macOS to 10.13, it now hangs at:

    + check_core_dumps --delete quiet
    + local del=
    + test --delete = --delete
    + del=1
    + shift
    + local app=quiet
    + test osx = osx
    ++ find /cores/ -type f -print
    + local 'cores=/cores//core.554
    /cores//core.641
    /cores//core.801'
    + test -z '/cores//core.554
    /cores//core.641
    /cores//core.801'
    + local core
    + for core in '$cores'
    + test 1 = 1
    + print_core quiet /cores//core.554
    + local app=quiet
    + local core=/cores//core.554
    + test quiet = quiet
    + echo 'Found core /cores//core.554'
    Found core /cores//core.554
    + return 0
    + rm /cores//core.554
    override r--------  root/admin for /cores//core.554?

The cores are always present on the Travis macOS 10.13 image! Hilarious.

Do this at the test-framework level instead of CI (Travis) scripts.
Then it works for QuickBuild and AppVeyor.

ref eb6dd3e42dc38460e8624dc5faef894e21c6aa26

a36938500988 fixed this for "~/.cache/nvim-deps/", but strangely not for
"~/.cache/nvim-deps-downloads/".

ref a36938500988
ref #8316
ref #8281

Seen in https://travis-ci.org/neovim/neovim/jobs/414982972 :

    Using third-party dependencies from Travis cache (last update: Aug 11 23:00:15 2018).
    cp: /Users/travis/build/neovim/neovim/deps-downloads/nvim-deps-downloads/…/nvim-deps-downloads/libvterm/a9c7c6fd20fa35e0ad3e0e98901ca12dfca9c25c.tar.gz:
    name too long (not copied)

closes #8281

ref #5166

This change was missed in c7f95fde1bb1.
ref #5166

Use `cp -r` instead of `mv`.
Remove use of `dirname`, that was missed in 10cdf8c28621.

closes #5166