git clone deadlock

git

/ # ps aux
PID   USER     TIME   COMMAND
    1 root       0:01 /quay-builder
   11 root       0:00 git clone git@github.com:celtra/mab.git /tmp/build_pack052587788
   13 root       0:00 [ssh-git.sh]
   16 root       0:23 git index-pack --stdin --fix-thin --keep=fetch-pack 11 on ip-10-0-1-216.ec2.internal --check-self-contained-and-connected
   24 root       0:00 sh
   30 root       0:00 ps aux
/ # apk-install strace
fetch http://dl-4.alpinelinux.org/alpine/v3.1/main/x86_64/APKINDEX.tar.gz
(1/1) Installing strace (4.9-r1)
Executing busybox-1.22.1-r15.trigger
OK: 69 MiB in 29 packages
/ # strace -p 16
Process 16 attached
futex(0x7f85fca7aab8, FUTEX_WAIT, 17, NULL^CProcess 16 detached
 <detached ...>
/ # strace -p 11
Process 11 attached
read(7, ^CProcess 11 detached
/ # ls -l /proc/11/fd
total 0
lr-x------    1 root     root            64 Jul 22 19:50 0 -> /dev/null
l-wx------    1 root     root            64 Jul 22 19:50 1 -> pipe:[15438]
l-wx------    1 root     root            64 Jul 22 19:50 2 -> pipe:[15438]
l-wx------    1 root     root            64 Jul 22 19:50 4 -> pipe:[16445]
lr-x------    1 root     root            64 Jul 22 19:50 5 -> pipe:[16446]
lr-x------    1 root     root            64 Jul 22 19:50 7 -> pipe:[16456]
/ # ls -l /proc/16/fd
total 0
lr-x------    1 root     root            64 Jul 22 19:52 0 -> pipe:[16455]
l-wx------    1 root     root            64 Jul 22 19:52 1 -> pipe:[16456]
l-wx------    1 root     root            64 Jul 22 19:52 2 -> pipe:[15438]
lrwx------    1 root     root            64 Jul 22 19:52 3 -> /tmp/build_pack052587788/.git/objects/pack/tmp_pack_5J6Mcb
l-wx------    1 root     root            64 Jul 22 19:52 4 -> pipe:[16445]
lr-x------    1 root     root            64 Jul 22 19:52 5 -> pipe:[16446]
lr-x------    1 root     root            64 Jul 22 19:52 6 -> /tmp/build_pack052587788/.git/objects/pack/tmp_pack_5J6Mcb
lr-x------    1 root     root            64 Jul 22 19:52 7 -> /tmp/build_pack052587788/.git/objects/pack/tmp_pack_5J6Mcb
lr-x------    1 root     root            64 Jul 22 19:52 8 -> /tmp/build_pack052587788/.git/objects/pack