Restore usedevelop=True now that pip 19.1.1 restored the old behavior
Restore usedevelop=True now that pip 19.1.1 restored the old behavior

Fix #5167

Akasurde/pytest,alfredodeza/pytest,nicoddemus/pytest,pytest-dev/pytest,The-Compiler/pytest,tomviner/pytest,The-Compiler/pytest,RonnyPfannschmidt/pytest,tomviner/pytest,markshao/pytest,nicoddemus/pytest