Merge branch 'bugfix/scan_fail_when_no_ap_found_v3.1' into 'release/v3.1'

fix the bug when scan fail after STA failed to connect to a nonexistent AP (backport v3.1)

See merge request idf/esp-idf!4914
This commit is contained in:
Jiang Jiang Jian
2019-05-06 11:39:33 +08:00