[PATCH v2 10/10] git.c: ignore pager.* when launching builtin as dashed external

["Martin Ågren" <martin.agren@gmail.com>]

When running, e.g., `git -c alias.bar=foo bar`, we expand the alias and
execute `git-foo` as a dashed external. This is true even if git foo is
a builtin. That is on purpose, and is motivated in a comment which was
added in commit 441981bc ("git: simplify environment save/restore
logic", 2016-01-26).

Shortly before we launch a dashed external, and unless we have already
found out whether we should use a pager, we check `pager.foo`. This was
added in commit 92058e4d ("support pager.* for external commands",
2011-08-18). If the dashed external is a builtin, this does not match
that commit's intention and is arguably wrong, since it would be cleaner
if we let the "dashed external builtin" handle `pager.foo`.

This has not mattered in practice, but a recent patch taught `git-tag`
to ignore `pager.tag` under certain circumstances. But, when started
using an alias, it doesn't get the chance to do so, as outlined above.
That recent patch added a test to document this breakage.

Do not check `pager.foo` before launching a builtin as a dashed
external, i.e., if we recognize the name of the external as a builtin.
Change the test to use `test_expect_success`.

Signed-off-by: Martin Ågren <martin.agren@gmail.com>
---
One could address this in run_argv(), by making the second call to
execv_dashed_external() conditional on "!is_builtin()" whereas a builtin
would be started as "git foo". (Possibly after unrolling and cleaning up
the "while (1)"-loop.) That seems like the wrong fix for this particular
issue, but might be a wanted change on its own -- or maybe not --, since
it would mean one could relay, e.g., "-c baz" to "git -c baz foo" (but
only for builtins...).

 t/t7006-pager.sh | 2 +-
 git.c            | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/t/t7006-pager.sh b/t/t7006-pager.sh
index df258c5d4..8b2ffb1aa 100755
--- a/t/t7006-pager.sh
+++ b/t/t7006-pager.sh
@@ -201,7 +201,7 @@ test_expect_success TTY 'git tag -a respects --paginate' '
 	test -e paginated.out
 '
 
-test_expect_failure TTY 'git tag as alias ignores pager.tag with -a' '
+test_expect_success TTY 'git tag as alias ignores pager.tag with -a' '
 	# git-tag will be launched as a dashed external, which
 	# 1) is the source of a potential bug, and
 	# 2) is why we use test_config and not -c.
diff --git a/git.c b/git.c
index 82ac2a092..6b6d9f68e 100644
--- a/git.c
+++ b/git.c
@@ -559,7 +559,7 @@ static void execv_dashed_external(const char **argv)
 	if (get_super_prefix())
 		die("%s doesn't support --super-prefix", argv[0]);
 
-	if (use_pager == -1)
+	if (use_pager == -1 && !is_builtin(argv[0]))
 		use_pager = check_pager_config(argv[0]);
 	commit_pager_choice();
 
-- 
2.14.0.rc0