https://confluence.atlassian.com/bitbucket/rate-limits-668173227.html

git-lfs-stress.sh

#!/usr/bin/env bash

#export GIT_TRACE=1
#export GIT_CURL_VERBOSE=1

set -ex

lfs_explode() {
    cd "$i"
    while true; do
        echo "Starting git fetch $BASHPID"
        rm -rf .git/lfs
        git lfs fetch 2>&1 || break
        echo "Completed git fetch $BASHPID"
    done
    echo
    echo
    echo EXITED $BASHID
    exit 1
}

repo=$1
cnt=${2:-2}

dest=$(basename $repo)

trap "killall background" EXIT

if [ ! -d $dest ]; then
    git clone --depth 1 $repo $dest
fi

work=()
for i in $(seq $cnt); do
    work+=("${dest}${i}")
done


for i in ${work[*]}; do
    echo Fixing $i
    rm -rf ${i}
    cp -al ${dest} ${i}
    git -C ${i} config lfs.transfer.maxretries 10
    git -C ${i} lfs env
    git --no-pager -C ${i} config -l
    lfs_explode "$i" &
done

time wait -n
killall background
wait

test-bitbucket-rate-limit.sh

#!/usr/bin/env bash

# Bitbucket appears to rate limit ssh connections, launch several connections
# that repeatedly connect to ssh and exit until each returns a bad status.

#export GIT_TRACE_PACKET=1
#export GIT_TRACE=1
#export GIT_SSH_COMMAND="ssh -vvv"
#export GIT_CURL_VERBOSE=1

spin_bitbucket() {
    i=0
    t0=$(date +%s.%N)
    while true; do
        ssh -Tvvv git@bitbucket.org || break
        t1=$(date +%s.%N)
        i=$(($i + 1))
        rate=$(echo "scale=3; $i/($t1 - $t0)" | bc)
        echo ":: $(date) $0($BASHPID): iteration $i, rate = $rate req/s"
    done
}

trap "killall background" EXIT

# Default to 5 parallel processes
cnt=${1:-5}

for i in $(seq $cnt); do
    spin_bitbucket &
done

wait

Update, bitbucket wasn't an issue, a Palo Alto Network Firewall had overly aggressive application settings. Sigh.