[PATCH v2 1/2] t3701: avoid one-shot export for shell functions

["Rubén Justo" <rjusto@gmail.com>]

The common construct:

    VAR=VAL command args

is a common way to set and export one-shot variables within the scope of
executing a "command".

However, when "command" is a function which in turn executes the
"command", the behavior varies depending on the shell:

 ** Bash 5.2.21 **

    $ f () { bash -c 'echo A=$A'; }
    $ A=1 f
    A=1

 ** dash 0.5.12-9 **

    $ f () { bash -c 'echo A=$A'; }
    $ A=1 f
    A=1

 ** dash 0.5.10.2-6 **

    $ f () { bash -c 'echo A=$A'; }
    $ A=1 f
    A=

Note that POSIX is not specific about this behavior:

http://www.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_09_01

One of our CI jobs on GitHub Actions uses Ubuntu 20.04 running dash
0.5.10.2-6, so we failed the test t3701:51;  the "git add -p" being
tested did not get our custom GIT_PAGER, which broke the test.

Work it around by explicitly exporting the variable in a subshell.

Signed-off-by: Rubén Justo <rjusto@gmail.com>
---
 t/t3701-add-interactive.sh | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/t/t3701-add-interactive.sh b/t/t3701-add-interactive.sh
index c60589cb94..1b8617e0c1 100755
--- a/t/t3701-add-interactive.sh
+++ b/t/t3701-add-interactive.sh
@@ -616,7 +616,11 @@ test_expect_success TTY 'P handles SIGPIPE when writing to pager' '
 	test_when_finished "rm -f huge_file; git reset" &&
 	printf "\n%2500000s" Y >huge_file &&
 	git add -N huge_file &&
-	test_write_lines P q | GIT_PAGER="head -n 1" test_terminal git add -p
+	test_write_lines P q | (
+		GIT_PAGER="head -n 1" &&
+		export GIT_PAGER &&
+		test_terminal git add -p
+	)
 '
 
 test_expect_success 'split hunk "add -p (edit)"' '
-- 
2.45.1