Why are there CR in Lefthook outputs?

[hituzi-no-sippo]

Is this a bug?

Example

$ sh reproduce.sh
Lefthook version: 1.6.1 e69adc10c99fd8887673a8b18894082453c6ceaf
=========================================
cat --show-nonprinting a.txt
=========================================
M-bM-^UM--M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@
M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^
@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^UM-.
M-bM-^TM-^B M-pM-^_M-%M-^J lefthook v1.6.1  hook: ^[[1moutput^[[0m M-bM-^TM-^B
M-bM-^UM-0M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@
M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^
@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^UM-/
sync hooks: M-bM-^\M-^TM-oM-8M-^O (output)
M-bM-^TM-^C  hello-world M-bM-^]M-/

hello^M
world^M


  M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM
-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^T
M-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@M-bM-^TM-^@
summary: (done in 0.00 seconds)
M-bM-^\M-^TM-oM-8M-^O  hello-world

There are CR(^M) in Lefthook outputs.

hello^M
world^M

Configuration (lefthook.toml)

min_version = '1.6.1'

[output]
[output.commands]
[output.commands.hello-world]
run = "echo 'hello'\necho 'world'\n"

Shell to reproduce

reproduce.sh

#!/usr/bin/env sh

mkdir there_are_CR_in_output_of_lefthook
cd there_are_CR_in_output_of_lefthook

git init --quiet

cat<<'HERE'>lefthook.toml
min_version = '1.6.1'

[output]
[output.commands]
[output.commands.hello-world]
run = "echo 'hello'\necho 'world'\n"
HERE

FILE_NAME='lefthook'
OUTPUT_FILE='a.txt'

wget \
  --quiet \
  --output-document="$FILE_NAME" \
  https://github.com/evilmartians/lefthook/releases/download/v1.6.1/lefthook_1.6.1_Linux_x86_64

chmod +x "$FILE_NAME"

printf 'Lefthook version: %s\n' "$(./"$FILE_NAME" version -f)"

./"$FILE_NAME" run output > "$OUTPUT_FILE"

echo "========================================="
echo "cat --show-nonprinting $OUTPUT_FILE"
echo "========================================="
cat --show-nonprinting "$OUTPUT_FILE"

Environment

• OS: Ubuntu 20.04 (WSL2)

Thanks.