readFileStrict to avoid laziness bug

Fix laziness bug introduced in last release that breaks use of
--unlock-present and --hide-missing adjusted branches.

Since there is a writeFile of the same file immediately after readFile, it
may still have the file open for read (or may have happened to read it
already and closed it).

I was not able to reproduce the problem in brief testing, but this seems
obvious.

Sponsored-by: Luke Shumaker on Patreona

Annex/AdjustedBranch.hs

@@ -253,8 +253,8 @@ updateAdjustedBranch adj (AdjBranch currbranch) origbranch
 			-- has that have not yet been propigated back to the
 			-- origbranch.
 			_ <- propigateAdjustedCommits' origbranch adj commitlck
-				
-			origheadfile <- inRepo $ readFile . Git.Ref.headFile
+			
+			origheadfile <- inRepo $ readFileStrict . Git.Ref.headFile
 
 			-- Git normally won't do anything when asked to check
 			-- out the currently checked out branch, even when its
@@ -279,7 +279,7 @@ updateAdjustedBranch adj (AdjBranch currbranch) origbranch
 		unless ok $ case newheadfile of
 			Nothing -> noop
 			Just v -> preventCommits $ \_commitlck -> inRepo $ \r -> do
-				v' <- readFile (Git.Ref.headFile r)
+				v' <- readFileStrict (Git.Ref.headFile r)
 				when (v == v') $
 					writeFile (Git.Ref.headFile r) origheadfile
 

CHANGELOG

@@ -3,6 +3,8 @@ git-annex (10.20230330) UNRELEASED; urgency=medium
   * git-annex.cabal: Prevent building with unix-compat 0.7 which
     removed System.PosixCompat.User.
   * Sped up sqlite inserts 2x when built with persistent 2.14.5.0
+  * Fix laziness bug introduced in last release that breaks use
+    of --unlock-present and --hide-missing adjusted branches.
 
  -- Joey Hess <id@joeyh.name>  Fri, 31 Mar 2023 12:48:54 -0400