Issue #1521996 by quietone, dww, Sophie.SK, Carsten Müller, Spokje,...

Issue #1521996 by quietone, dww, Sophie.SK, Carsten Müller, Spokje, kim.pepper, izus, mjpa, ashu1629, AlanHDev, mangy.fox, Vivek Panicker, robpowell, jozzy_a, tar_inet, ravi.shankar, sokru, zuhair_ak, cjgratacos, aerozeppelin, darrenwh, lomasr, luismagr, mohit1604, ronald.garcia, matteodem, webchuck, gordon, nginex, jain_deepak, Aunion, ankitgarg, Elendev, Kristen Pol, alexpott, YesCT, dpi, no2e, larowlan, longwave, markpavlitski, acbramley, C_Logemann, cilefen, claudiu.cristea, penyaskito, David_Rothstein, Leeteq, anagp, jlbellido, pdrake, klausi: Password reset form reveals whether an email or username is in use