getUserEntryForID does not work on windows

Throw an error instead, mentioning the relevant env vars.

Utility/UserInfo.hs

@@ -48,8 +48,11 @@ myUserGecos = myVal [] userGecos
 #endif
 
 myVal :: [String] -> (UserEntry -> String) -> IO String
-myVal envvars extract = maybe (extract <$> getpwent) return =<< check envvars
+myVal envvars extract = go envvars
   where
-	check [] = return Nothing
-	check (v:vs) = maybe (check vs) (return . Just) =<< getEnv v
-	getpwent = getUserEntryForID =<< getEffectiveUserID
+#ifndef mingw32_HOST_OS
+	go [] = extract <$> (getUserEntryForID =<< getEffectiveUserID)
+#else
+	go [] = error $ "environment not set: " ++ show envvars
+#endif
+	go (v:vs) = maybe (go vs) return =<< getEnv v

doc/bugs/annex_get_fails_from_read-only_filesystem/comment_6_c469f1fe8ae6981a038be7f8723a07b1._comment

@@ -0,0 +1,7 @@
+[[!comment format=mdwn
+ username="joey"
+ subject="""comment 6"""
+ date="2014-10-31T16:55:47Z"
+ content="""
+An upgrade could move the annexed objects around.
+"""]]