[PATCH 02/19] t1010: fix unnoticed failure on Windows

On Microsoft Windows, a directory name should never end with a period. Quoting from Microsoft documentation[1]:

    Do not end a file or directory name with a space or a period.
    Although the underlying file system may support such names, the
    Windows shell and user interface does not.

Naming a directory with a trailing period is indeed perilous:

    % git init foo
    % cd foo
    % mkdir a.
    % git status
    warning: could not open directory 'a./': No such file or directory

The t1010 "setup" test:

    for d in a a. a0
    do
        mkdir "$d" && echo "$d/one" >"$d/one" &&
        git add "$d"
    done &&

runs afoul of this Windows limitation, as can be observed when running the test verbosely:

    error: open("a./one"): No such file or directory
    error: unable to index file 'a./one'
    fatal: adding files failed

The reason this problem has gone unnoticed for so long is twofold. First, the failed `git add` is swallowed silently because the loop is not terminated explicitly by `|| return 1` to signal the failure. Second, none of the tests in this script care about the actual directory names or even the number of tree entries. They care only that the tree synthesized in the index and created by `git write-tree` matches the tree created by the output of `git ls-tree` fed into `git mktree`, and the failure of `git add "a./one"` doesn't change that outcome.

Skipping these tests on Windows by, for instance, checking the FUNNYNAMES predicate would avoid the problem, however, the funny-looking name is not what is being tested here. Rather, the tests are about checking that `git mktree` produces stable results for various input conditions, such as when the input order is not consistent or when an object is missing.

Therefore, resolve the problem simply by using a directory name which is legal on Windows (i.e. "a-" rather than "a."). While at it, add the missing `|| return 1` to the loop body in order to catch this sort of problem in the future.

[1]: https://docs.microsoft.com/en-us/windows/win32/fileio/naming-a-file

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
---
 t/t1010-mktree.sh | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)