Don't use v1 cached captchas for new threads. #1300

src/Posting/Captcha.cache.coffee

@@ -21,9 +21,11 @@ Captcha.cache =
     @captchas = captchas
     @count()
 
-  getOne: ->
+  getOne: (isReply) ->
     @clear()
-    if (captcha = @captchas.shift())
+    i = @captchas.findIndex((x) -> isReply or !x.challenge?)
+    if i >= 0
+      captcha = @captchas.splice(i, 1)[0]
       $.set 'captchas', @captchas
       @count()
       captcha

src/Posting/Captcha.v1.coffee

@@ -134,8 +134,8 @@ Captcha.v1 =
     delete @occupied
     @beforeSetup() if @nodes
 
-  getOne: ->
-    if (captcha = Captcha.cache.getOne())
+  getOne: (isReply) ->
+    if (captcha = Captcha.cache.getOne isReply)
       captcha
     else
       challenge = @nodes.img.alt

src/Posting/Captcha.v2.coffee

@@ -153,8 +153,8 @@ Captcha.v2 =
       $.rm node
     return
 
-  getOne: ->
-    Captcha.cache.getOne()
+  getOne: (isReply) ->
+    Captcha.cache.getOne isReply
 
   save: (pasted, token) ->
     Captcha.cache.save

src/Posting/QR.coffee

@@ -621,7 +621,7 @@ QR =
       err or= 'Original comment required.'
 
     if QR.captcha.isEnabled and !err
-      captcha = QR.captcha.getOne()
+      captcha = QR.captcha.getOne(!!threadID)
       unless captcha
         err = 'No valid captcha.'
         QR.captcha.setup(!QR.cooldown.auto or d.activeElement is QR.nodes.status)