diff --git a/Annex/Branch.hs b/Annex/Branch.hs
index a3945a18c1..e465b75326 100644
--- a/Annex/Branch.hs
+++ b/Annex/Branch.hs
@@ -223,10 +223,15 @@ getLocal :: FilePath -> Annex String
 getLocal file = go =<< getJournalFileStale file
   where
 	go (Just journalcontent) = return journalcontent
-	go Nothing = getRaw file
+	go Nothing = getRef fullname file
 
-getRaw :: FilePath -> Annex String
-getRaw = getRef fullname
+{- Gets the content of a file as staged in the branch's index. -}
+getStaged :: FilePath -> Annex String
+getStaged = getRef indexref
+  where
+	-- This makes git cat-file be run with ":file",
+	-- so it looks at the index.
+	indexref = Ref ""
 
 getHistorical :: RefDate -> FilePath -> Annex String
 getHistorical date file =
@@ -533,6 +538,10 @@ performTransitionsLocked jl ts neednewlocalbranch transitionedrefs = do
 	-- update the git-annex branch, while it usually holds changes
 	-- for the head branch. Flush any such changes.
 	Annex.Queue.flush
+	-- Stop any running git cat-files, to ensure that the
+	-- getStaged calls below use the current index, and not some older
+	-- one.
+	catFileStop
 	withIndex $ do
 		prepareModifyIndex jl
 		run $ mapMaybe getTransitionCalculator tlist
@@ -557,15 +566,15 @@ performTransitionsLocked jl ts neednewlocalbranch transitionedrefs = do
 	 - to hold changes to every file in the branch at once.)
 	 -
 	 - When a file in the branch is changed by transition code,
-	 - that value is remembered and fed into the code for subsequent
+	 - its new content is remembered and fed into the code for subsequent
 	 - transitions.
 	 -}
 	run [] = noop
 	run changers = do
-		trustmap <- calcTrustMap <$> getRaw trustLog
+		trustmap <- calcTrustMap <$> getStaged trustLog
 		fs <- branchFiles
 		forM_ fs $ \f -> do
-			content <- getRaw f
+			content <- getStaged f
 			apply changers f content trustmap
 	apply [] _ _ _ = return ()
 	apply (changer:rest) file content trustmap =
diff --git a/CHANGELOG b/CHANGELOG
index 8e1b0eb1f1..908c42b03f 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -11,6 +11,8 @@ git-annex (6.20180720) UNRELEASED; urgency=medium
   * Fix wrong sorting of remotes when using -J, it was sorting by uuid,
     rather than cost.
   * addurl: Include filename in --json-progress output.
+  * Fix git-annex branch data loss that could occur after
+    git-annex forget --drop-dead.
 
  -- Joey Hess <id@joeyh.name>  Tue, 31 Jul 2018 12:14:11 -0400
 
diff --git a/doc/bugs/git_annex_forget_--drop-dead_can_lose_group_information.mdwn b/doc/bugs/git_annex_forget_--drop-dead_can_lose_group_information.mdwn
index c9e94389e6..5c76e9494f 100644
--- a/doc/bugs/git_annex_forget_--drop-dead_can_lose_group_information.mdwn
+++ b/doc/bugs/git_annex_forget_--drop-dead_can_lose_group_information.mdwn
@@ -152,3 +152,5 @@ B IS IN GROUP:
 ### 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)
 
 Yes, git-annex is slowly replacing all of my other sync and backup systems I've cobbled together over the years.
+
+> [[fixed|done]] --[[Joey]]
diff --git a/doc/bugs/git_annex_forget_--drop-dead_can_lose_group_information/comment_1_f4b78aeaf9163b374254c08057222661._comment b/doc/bugs/git_annex_forget_--drop-dead_can_lose_group_information/comment_1_f4b78aeaf9163b374254c08057222661._comment
new file mode 100644
index 0000000000..75bd9bd1ac
--- /dev/null
+++ b/doc/bugs/git_annex_forget_--drop-dead_can_lose_group_information/comment_1_f4b78aeaf9163b374254c08057222661._comment
@@ -0,0 +1,25 @@
+[[!comment format=mdwn
+ username="joey"
+ subject="""comment 1"""
+ date="2018-08-06T19:49:06Z"
+ content="""
+Great bug report!
+
+There is a general data loss problem in this scenario, it's not specific to
+group changes at all. Changes that were only present in a sibling git-annex
+branch are not being preserved when the repository updates its git-annex
+branch index file for a transition.
+
+The index file lacking those changes then gets committed with the sibling
+branches as parent(s). So the changes are effectively reverted.
+
+The root cause is that the handleTransitions uses getRaw
+to get the contents of files. That uses git cat-file git-annex:$file, which
+gets the version last committed to the git-annex branch,
+not the version from the git-annex branch index file. And handleTransitions is
+run after all sibling branches have been union merged in the index file
+but not committed yet. 
+
+The fix is to instead use git cat-file :$file, so it will get the version
+from the index. 
+"""]]
diff --git a/doc/bugs/git_annex_forget_--drop-dead_can_lose_group_information/comment_2_1468e26d2da85bcaf50715fbe3c38490._comment b/doc/bugs/git_annex_forget_--drop-dead_can_lose_group_information/comment_2_1468e26d2da85bcaf50715fbe3c38490._comment
new file mode 100644
index 0000000000..8fe3936bc1
--- /dev/null
+++ b/doc/bugs/git_annex_forget_--drop-dead_can_lose_group_information/comment_2_1468e26d2da85bcaf50715fbe3c38490._comment
@@ -0,0 +1,19 @@
+[[!comment format=mdwn
+ username="joey"
+ subject="""comment 2"""
+ date="2018-08-06T21:26:36Z"
+ content="""
+If you lost things from the git-annex branch due this bug, 
+you can find the commit that contained them by `git log git-annex`,
+and look for the commit before the "continuing transition" commit.
+
+It's then possible to get those changes applied back to the git-annex
+brannch; there should be no permanent data loss due to this bug.
+
+Eg, here the commit that contained the lost group change was
+261d1be6a2093f1e4059ed3030016c365f29413f. To get that back into the
+git-annex branch, I ran:
+
+	git update-ref git-annex 261d1be6a2093f1e4059ed3030016c365f29413f
+	git annex merge
+"""]]