webapp: Fixed a crash when adding a git remote.

Reversion introduced in 2b66492d6e which added a new cache that needs to be
cleared.

CHANGELOG

@@ -49,6 +49,8 @@ git-annex (7.20181025) UNRELEASED; urgency=medium
   * addurl: Removed undocumented special case in handling of a CHECKURL-MULTI
     response with only a single file listed. Rather than ignoring the url that
     was in the response, use it.
+  * webapp: Fixed a crash when adding a git remote.
+    (Reversion introduced in version 6.20180112)
 
  -- Joey Hess <id@joeyh.name>  Sat, 13 Oct 2018 00:52:02 -0400
 

Remote/List.hs

@@ -93,6 +93,7 @@ remoteListRefresh = do
 	newg <- inRepo Git.Config.reRead
 	Annex.changeState $ \s -> s 
 		{ Annex.remotes = []
+		, Annex.gitremotes = Nothing
 		, Annex.repo = newg
 		}
 	remoteList

doc/bugs/Can__39__t_add_remotes_through_the_web_assistant.mdwn

@@ -108,3 +108,4 @@ The interesting part here is that if I try to run the failing git commands in th
 ### Have you had any luck using git-annex before? (Sometimes we get tired of reading bug reports all day and a lil' positive end note does wonders)
 I have been using it for years. Just not the webapp :)
 
+> [[fixed|done]] --[[Joey]] 

doc/bugs/Can__39__t_add_remotes_through_the_web_assistant/comment_8_4415e7897cca54e004f3cb06031753ae._comment

@@ -0,0 +1,20 @@
+[[!comment format=mdwn
+ username="joey"
+ subject="""comment 8"""
+ date="2018-10-29T19:36:51Z"
+ content="""
+Sorry for leaving such a bad bug unaddressed so long. (And in fact a
+reversion since it used to work fine and I broke it about a month before
+this bug was opened.)
+
+It's fixed now.
+
+Bear in mind that I have a backlog that is literally
+over 400 items long and just can't get to everything promptly. 
+Unsure why I didn't notice one of the several followups in my 
+triage operations, other than the assistant being a ways down
+my prority list and bug reports about it often being not detailed enough
+and taking a lot of time to understand. If anyone would like to help
+triage out important problems like this one that I may be missing,
+that would be great.
+"""]]