Regression in Artifactory 6.9 in conan search with properties queries

Github ticket: https://github.com/conan-io/conan/issues/4951

The queries

conan search my-product/1.0.0@usr/stable -q "(build_type=Release AND os=Windows) OR os=Linux" -r repo

Worked in previous versions, now it is failing with:

ERROR: Unknown query key: (build_type. [Remote: releases]

Tested previous versions of Artifactory CE down to 6.3, they worked fine. Artifactory 6.9.1 also fails.

Steps to reproduce:

• Start Artifactory CE 6.9.1 (in Windows, double click on .bat launcher)
• Create a conan local repo, named "repo" in Artifactory
• Set the remote "repo" in a conan client (conan 1.14.3, Windows)
• Create and upload a conan package (with binary)
• conan search my-product/1.0.0@usr/stable -q "(build_type=Release AND os=Windows)" -r repo

As a python script: 

import os
os.system("conan new pkg/0.1 --bare")
os.system("conan create . pkg/0.1@user/testing")
os.system("conan remote add local http://localhost:8081/artifactory/api/conan/conan-local -f")
os.system("conan upload pkg/0.1@user/testing -r=local --all")
os.system('conan search pkg/0.1@user/testing -r=local -q "(build_type=Release AND os=Windows)"')

Same steps with a previous Artifactory work fine

28-08-2020: Latest Artifactory (7.6.3) is still failling. The problem has a workaround in the Conan client from version 1.20 (see bellow) but can be reproduced calling the endpoint in Artifactory with a query like this one:

curl -uadmin:conan2020 'http://localhost:8081/artifactory/api/conan/conan-local/v1/conans/pkg/0.1/user/testing/search?q=%28build_type%3DRelease+AND+os%3DMacos%29'

Workaround:

28-08-2020: From Conan 1.20 the query filtering is made on the Conan side with this fix: https://github.com/conan-io/conan/pull/5960 but the problem in Artifactory still persists.