Fixed Issue #1468

packages/rocketchat-lib/server/functions/setUsername.coffee

 RocketChat.setUsername = (user, username) ->
+	console.log("In setUserName")
 	username = s.trim username
 	if not user or not username
 		return false
@@ -10,12 +11,15 @@ RocketChat.setUsername = (user, username) ->
 	if user.username is username
 		return user
 
-	# Check username availability
-	unless RocketChat.checkUsernameAvailability username
-		return false
-
 	previousUsername = user.username
 
+	# Check username availability or if the user already owns a different casing of the name
+	if ( !previousUsername or !(username.toLowerCase() == previousUsername.toLowerCase()))
+		unless RocketChat.checkUsernameAvailability username
+			return false
+
+
+
 	# If first time setting username, send Enrollment Email
 	if not previousUsername and RocketChat.settings.get 'Accounts_Enrollment_Email'
 		Accounts.sendEnrollmentEmail(user._id)

packages/rocketchat-lib/server/methods/setUsername.coffee

@@ -16,8 +16,13 @@ Meteor.methods
 		if not /^[0-9a-zA-Z-_.]+$/.test username
 			throw new Meteor.Error 'username-invalid', "#{username} is not a valid username, use only letters, numbers, dots and dashes"
 
-		if not RocketChat.checkUsernameAvailability username
-			throw new Meteor.Error 'username-unavailable', "#{username} is already in use :("
+		if user.username != undefined
+			if not username.toLowerCase() == user.username.toLowerCase() 
+				if not  RocketChat.checkUsernameAvailability username
+					throw new Meteor.Error 'username-unavailable', "#{username} is already in use :("
+		else
+			if not  RocketChat.checkUsernameAvailability username
+				throw new Meteor.Error 'username-unavailable', "#{username} is already in use :("
 
 		unless RocketChat.setUsername user, username
 			throw new Meteor.Error 'could-not-change-username', "Could not change username"