Test failures on OpenBSD

["Ævar Arnfjörð Bjarmason" <avarab@gmail.com>]

This is on OpenBSD 6.2 amd64 with my "tests: fix and add lint for
non-portable head -c N" patch (which fixes one failure).

    $ for t in t1305-config-include.sh t1308-config-set.sh t5004-archive-corner-cases.sh t5552-skipping-fetch-negotiator.sh; do ./$t --no-color -v -x 2>&1 | grep -B10 "^not ok"; done
    
    + cd bar
    + echo [includeIf "gitdir:bar/"]path=bar7
    + >> .git/config 
    + echo [test]seven=7
    + > .git/bar7 
    + echo 7
    + > expect 
    + git config test.seven
    + > actual 
    error: last command exited with $?=1
    not ok 27 - conditional include, gitdir matching symlink
    --
    + cd bar
    + echo [includeIf "gitdir/i:BAR/"]path=bar8
    + >> .git/config 
    + echo [test]eight=8
    + > .git/bar8 
    + echo 8
    + > expect 
    + git config test.eight
    + > actual 
    error: last command exited with $?=1
    not ok 28 - conditional include, gitdir matching symlink, icase
    	test_cmp expect actual
    
    + echo Error (-1) reading configuration file a-directory.
    + > expect 
    + mkdir a-directory
    + test_expect_code 2 test-tool config configset_get_value foo.bar a-directory
    + 2> output 
    Value not found for "foo.bar"
    test_expect_code: command exited with 1, we wanted 2 test-tool config configset_get_value foo.bar a-directory
    error: last command exited with $?=1
    not ok 23 - proper error on directory "files"
    + make_dir extract
    + tar xf subtree-all.tar -C extract
    tar: Cannot identify format. Searching...
    tar: End of archive volume 1 reached
    tar: Sorry, unable to determine archive format.
    error: last command exited with $?=1
    + rm -rf extract
    + exit 1
    + eval_ret=1
    + :
    not ok 9 - archive empty subtree with no pathspec
    --
    + make_dir extract
    + tar xf subtree-path.tar -C extract
    tar: Cannot identify format. Searching...
    tar: End of archive volume 1 reached
    tar: Sorry, unable to determine archive format.
    error: last command exited with $?=1
    + rm -rf extract
    + exit 1
    + eval_ret=1
    + :
    not ok 10 - archive empty subtree by direct pathspec
    'git <command> [<revision>...] -- [<file>...]'
    fatal: ambiguous argument 'c7': unknown revision or path not in the working tree.
    Use '--' to separate paths from revisions, like this:
    'git <command> [<revision>...] -- [<file>...]'
    No have c7 (c7)
    error: last command exited with $?=1
    + test_unconfig -C client fetch.negotiationalgorithm
    + exit 1
    + eval_ret=1
    + :
    not ok 1 - commits with no parents are sent regardless of skip distance
    --
     Author: A U Thor <author@example.com>
     1 file changed, 1 insertion(+)
     create mode 100644 to_fetch.t
    + git init client
    Initialized empty Git repository in /home/avar/g/git/t/trash directory.t5552-skipping-fetch-negotiator/client/.git/
    + seq 11
    ./t5552-skipping-fetch-negotiator.sh: seq: not found
    + git -C client checkout c5
    error: pathspec 'c5' did not match any file(s) known to git
    error: last command exited with $?=1
    not ok 3 - when two skips collide, favor the larger one
    --
    + git init client
    Initialized empty Git repository in /home/avar/g/git/t/trash directory.t5552-skipping-fetch-negotiator/client/.git/
    + seq 8
    ./t5552-skipping-fetch-negotiator.sh: seq: not found
    + seq 19
    ./t5552-skipping-fetch-negotiator.sh: seq: not found
    + pwd
    + git -C server fetch --no-tags /home/avar/g/git/t/trash directory.t5552-skipping-fetch-negotiator/client b1:refs/heads/b1
    fatal: Couldn't find remote ref b1
    error: last command exited with $?=128
    not ok 6 - do not send "have" with ancestors of commits that server ACKed

Full output at https://gitlab.com/snippets/1747801

Some of this, like the t5552-skipping-fetch-negotiator.sh failures are
new in 2.19.0 (those go away with s/seq/test_seq). But some are
older. E.g. the archive corner cases failure is becuse that test wants
unzip & GNU tar, which OpenBSD upstream has patched already:
https://github.com/openbsd/ports/blob/master/devel/git/patches/patch-t_test-lib_sh