Victoriametrics: escape char in `by` not work

[n4mine]

Describe the bug
sum(ooo) by (k\|v) is not work. k|v is a label key.

To Reproduce

while : ; do v=$(date +%s) ; echo $v ; curl -d "ooo,k=$(shuf -i 1-5 | head -1),k|v=$(shuf -i 1-5 | head -1) v=${v} ${v}000000000" -X POST 'http://127.0.0.1:8428/write'  ; sleep 1 ; done

escape label key works fine

by non escape k works fine

by escape k not work

Expected behavior
sum(ooo) by (k\|v) works as sum(ooo) by (k)

Version
The line returned when passing --version command line flag to binary. For example:

./bin/victoria-metrics -version
victoria-metrics-20200903-090605-heads-master-0-g764b3d4f

[valyala]

The bug must be fixed in the commit d5b985f086542de3ec1c472f1a47b2bb90798e93 .

@n4mine , could you build VictoriaMetrics from this commit according to these instructions and verify whether the bug is fixed there?

[n4mine]

thank you @valyala

it's fixed.

[valyala]

The bugfix will be included in v1.40.1.