grep: align --exclude-standard and subdirectory --untracked behavior with Git

[genedna]

Summary

libra grep diverges from Git in two independently reproducible parts of the upstream scenario t7810-grep.sh test 200 (inside git repository but with --no-index):

1. grep --no-index --exclude-standard is rejected as an unsupported option.
2. From a subdirectory, grep --untracked searches from the repository root instead of limiting output to the current directory.

This is tracked by libra-testcases as TC-1596. Merely normalizing Git's .gitignore to Libra's .libraignore is insufficient because both differences affect behavior, not just output wording.

Versions

• Libra: 0.22.19
• Git control: 2.55.0.782.g1630431f32
• Platform: macOS, case-insensitive APFS
• Upstream source: Git commit 1630431f326e15fcde608827b5ff38422528eb59, t/t7810-grep.sh lines 1288-1328

Reproduction

Run the following with LIBRA set to the Libra binary:

set -eu

work=$(mktemp -d)
trap 'rm -rf "$work"' EXIT

"$LIBRA" init -q --initial-branch=main "$work/repo"
mkdir -p "$work/repo/sub"
printf 'hello\n' >"$work/repo/file1"
printf 'world\n' >"$work/repo/sub/file2"
printf '.*o*\n' >"$work/repo/.libraignore"

cd "$work/repo"
"$LIBRA" grep --no-index --exclude-standard o

cd sub
"$LIBRA" grep --untracked o

The equivalent Git setup uses .gitignore with the same contents.

Actual behavior

At the repository root:

$ libra grep --no-index --exclude-standard o
error: unexpected argument '--exclude-standard' found
Error-Code: LBR-CLI-002
Usage: libra grep --no-index [PATTERN] [PATHS]...

The command exits 129 and produces no matches.

From repo/sub:

$ libra grep --untracked o
file1:hello
sub/file2:world

The command exits 0 but includes a file outside the current subdirectory and uses repository-root-relative paths.

Expected behavior

At the repository root, matching Git:

$ git grep --no-index --exclude-standard o
file1:hello
sub/file2:world

The command should exit 0. --exclude-standard should apply the product's native standard ignore rules, excluding the matching native ignore file.

From repo/sub, matching Git's current-directory scope:

$ git grep --untracked o
file2:world

The command should exit 0, omit root-level file1, and report paths relative to the current subdirectory.

Additional observations

These parts already behave equivalently after mapping the native ignore filenames:

• grep o: both exit 1 with no output in the new repository.
• grep --untracked o from the repository root: both output file1:hello and sub/file2:world.
• grep --no-index o from the repository root: both output the native ignore file plus the two matching content files.
• grep --no-index o from sub: both output only file2:world.

The original upstream-style Libra run stops earlier because --no-index also sees Libra's automatically generated .libraignore; a native-interface comparison removes that superficial difference and exposes the two behavioral gaps above.