Fix support for readonly git remotes

Boolean blindness oops.

(Reversion in version 8.20210621)

Sponsored-by: Dartmouth College's Datalad project

CHANGELOG

@@ -24,6 +24,8 @@ git-annex (8.20210804) UNRELEASED; urgency=medium
     servers.
   * add: Detect when xattrs or perhaps ACLs prevent locking down
     a file's content, and fail with an informative message.
+  * Fix support for readonly git remotes.
+    (Reversion in version 8.20210621)
 
  -- Joey Hess <id@joeyh.name>  Tue, 03 Aug 2021 12:22:45 -0400
 

Database/Keys.hs

@@ -75,7 +75,7 @@ runReader a = do
 		v <- a (SQL.ReadHandle qh)
 		return (v, st)
 	go DbClosed = do
-		st' <- openDb True DbClosed
+		st' <- openDb False DbClosed
 		v <- case st' of
 			(DbOpen qh) -> a (SQL.ReadHandle qh)
 			_ -> return mempty
@@ -97,7 +97,7 @@ runWriter a = do
 		v <- a (SQL.WriteHandle qh)
 		return (v, st)
 	go st = do
-		st' <- openDb False st
+		st' <- openDb True st
 		v <- case st' of
 			DbOpen qh -> a (SQL.WriteHandle qh)
 			_ -> error "internal"

doc/bugs/unable_to_get_content_via_ssh_without_write_perms/comment_3_a4f9bb23f0682a66e951b96aed6ae214._comment

@@ -0,0 +1,13 @@
+[[!comment format=mdwn
+ username="joey"
+ subject="""comment 3"""
+ date="2021-08-30T16:24:52Z"
+ content="""
+reversion in [[!commit f46e4c9b7c]], which reversed some logic and made
+database reads be treated as database writes, so they failed on permission
+denied, rather than the right behavior of returning DbUnavailable. Fixed that. 
+
+I have not been able to reproduce the other error involving
+opening a temp file. All I can tell from the message is that it's writing
+to some file in .git/annex via a temp file in the same directory.
+"""]]