avoid crashing tilde expansion on user who does not exist

git does not crash when there's a remote configured for a user who does
not exist, and this prevents git-annex from crashing too. Consider that
a user might exist on one system but not another, and the git repo be
moved between systems. So not crashing is desirable.

Note that git fetch seems to mishandle a remote path like ~foo/bar
when the user does not exist. While it does access ./~foo/bar,
and gets as far as running git-upload-pack on the path,
it then complains there is no such repo. So different parts of git seem
to be doing different things in that edge case. Anyway, git-annex does
not need to be bug-for-bug compatible with git.

Sponsored-by: Jack Hill on Patreon

CHANGELOG

@@ -9,6 +9,7 @@ git-annex (8.20211012) UNRELEASED; urgency=medium
     by versions of git-annex older than 6.20180312.
   * test: Put gpg temp home directory in system temp directory,
     not filesystem being tested.
+  * Avoid crashing tilde expansion on user who does not exist.
 
  -- Joey Hess <id@joeyh.name>  Mon, 11 Oct 2021 14:09:13 -0400
 

Git/Construct.hs

@@ -184,7 +184,10 @@ expandTilde :: FilePath -> IO FilePath
 #ifdef mingw32_HOST_OS
 expandTilde = return
 #else
-expandTilde = expandt True
+expandTilde p = expandt True p
+	-- If unable to expand a tilde, eg due to a user not existing,
+	-- use the path as given.
+	`catchNonAsync` (const (return p))
   where
 	expandt _ [] = return ""
 	expandt _ ('/':cs) = do