Errors testing on macOS High Sierra version 10.13.4

[Wink Saville <wink@saville.com>]

I built git on a mac osx laptop and got some errors when testing.
I ran ./ci/run-build-and-tests.sh and three of the tests had failures
that appear to be associated with character encoding:
...
    BUILTIN git-whatchanged
    SUBDIR git-gui
    SUBDIR gitk-git
    SUBDIR templates
+ make --quiet test
*** prove ***
[07:58:38] t0204-gettext-reencode-sanity.sh ...................
Dubious, test returned 1 (wstat 256, 0x100)
Failed 1/8 subtests
[07:58:39] t0050-filesystem.sh ................................
Dubious, test returned 1 (wstat 256, 0x100)
Failed 2/10 subtests
[07:58:42] t9822-git-p4-path-encoding.sh ......................
Dubious, test returned 1 (wstat 256, 0x100)
Failed 3/6 subtests
[08:00:55] t9001-send-email.sh ................................ ok   132492 ms
[08:01:00] t3421-rebase-topology-linear.sh .................... ok   139911 ms
[08:01:08] t3404-rebase-interactive.sh ........................ ok   146923 ms
[08:02:42] t3903-stash.sh ..................................... ok   101289 ms
...

And here is one of the errors from t0204:

$ cat t0204-gettext-reencode-sanity.out
Initialized empty Git repository in /Users/wink/prgs/git/git/t/trash
directory.t0204-gettext-reencode-sanity/.git/
# lib-gettext: Found 'is_IS.UTF-8' as an is_IS UTF-8 locale
# lib-gettext: Found 'is_IS.ISO8859-1' as an is_IS ISO-8859-1 locale
...
++ eval_ret=0
++ :
ok 7 - gettext.c: git init UTF-8 -> UTF-8

expecting success:
    printf "Bjó til tóma Git lind" >expect &&
    LANGUAGE=is LC_ALL="$is_IS_iso_locale" git init repo >actual &&
    test_when_finished "rm -rf repo" &&
    grep "^$(cat expect | iconv -f UTF-8 -t ISO8859-1) " actual
++ printf 'Bjó til tóma Git lind'
++ LANGUAGE=is
++ LC_ALL=is_IS.ISO8859-1
++ git init repo
++ test_when_finished 'rm -rf repo'
++ test 0 = 0
++ test_cleanup='{ rm -rf repo
} && (exit "$eval_ret"); eval_ret=$?; :'
+++ cat expect
+++ iconv -f UTF-8 -t ISO8859-1
++ grep '^Bj? til t?ma Git lind ' actual
error: last command exited with $?=1
++ rm -rf repo
++ exit 1
++ eval_ret=1
++ :
not ok 8 - gettext.c: git init UTF-8 -> ISO-8859-1
#
#     printf "Bjó til tóma Git lind" >expect &&
#     LANGUAGE=is LC_ALL="$is_IS_iso_locale" git init repo >actual &&
#     test_when_finished "rm -rf repo" &&
#     grep "^$(cat expect | iconv -f UTF-8 -t ISO8859-1) " actual
#

# failed 1 among 8 test(s)
1..8


Of course on travis-ci there are no failures so I dug deeper and found
that travis-ci is running 10.12.6 (I added a call to system_profier in
ci/run-build-and-tests.sh) where as I'm running is 10.13.4:

+system_profiler SPSoftwareDataType
Software:
    System Software Overview:
      System Version: macOS 10.12.6 (16G29)
      Kernel Version: Darwin 16.7.0
      Boot Volume: Macintosh HD
      Boot Mode: Normal
      Computer Name: Travis’s Mac (294)
      User Name: Travis (travis)
      Secure Virtual Memory: Enabled
      System Integrity Protection: Enabled
      Time since boot: 5 minutes

Not sure, but maybe I've got something configured incorrectly.

Suggestions anyone?

-- Wink