Fix Pex REPL prompt. #3250

Job	Run time
Check GitHub Organization	1s
tox -e format-check,lint-check,typecheck,enum-check,vendor-check,package,docs	10m 38s
./dtox.sh -e py27-pip20	9m 57s
tox -e py313-pip24_3_1	12m 18s
./dtox.sh -e py38-pip22_3_1	17m 59s
tox -e py313-pip24_3_1-integration --shard 1/2	30m 7s
./dtox.sh -e py311-pip23_3_2	19m 14s
tox -e py313-pip24_3_1-integration --shard 2/2	28m 50s
./dtox.sh -e py313-pip24_3_1	15m 2s
./dtox.sh -e py314-pip24_3_1	25m 36s
./dtox.sh -e pypy310-pip24_3_1	27m 21s
./dtox.sh -e py27-pip20-integration	28m 9s
./dtox.sh -e py38-pip22_3_1-integration --shard 1/2	30m 57s
./dtox.sh -e py38-pip22_3_1-integration --shard 2/2	28m 4s
./dtox.sh -e py311-pip23_3_2-integration --shard 1/2	30m 39s
./dtox.sh -e py311-pip23_3_2-integration --shard 2/2	29m 18s
./dtox.sh -e py313-pip24_3_1-integration --shard 1/2	29m 7s
./dtox.sh -e py313-pip24_3_1-integration --shard 2/2	26m 46s
./dtox.sh -e py314-pip24_3_1-integration --shard 1/2	33m 49s
./dtox.sh -e py314-pip24_3_1-integration --shard 2/2	28m 46s
./dtox.sh -e pypy310-pip24_3_1-integration --shard 1/2	49m 13s
./dtox.sh -e pypy310-pip24_3_1-integration --shard 2/2	47m 32s
Gather Final Status	1s
	9h 19m 24s

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