fix repo description setting bugs

* init: When the repository already has a description, don't change it.
* describe: When run with no description parameter it used to set
  the description to "", now it will error out.

Annex/Init.hs

@@ -1,6 +1,6 @@
 {- git-annex repository initialization
  -
- - Copyright 2011-2017 Joey Hess <id@joeyh.name>
+ - Copyright 2011-2019 Joey Hess <id@joeyh.name>
  -
  - Licensed under the GNU AGPL version 3 or higher.
  -}
@@ -52,6 +52,8 @@ import System.Posix.User
 import qualified Utility.LockFile.Posix as Posix
 #endif
 
+import qualified Data.Map as M
+
 checkCanInitialize :: Annex a -> Annex a
 checkCanInitialize a = inRepo (noAnnexFileContent . Git.repoWorkTree) >>= \case
 	Nothing -> a
@@ -88,7 +90,10 @@ initialize mdescription mversion = checkCanInitialize $ do
 	initSharedClone sharedclone
 
 	u <- getUUID
-	describeUUID u =<< genDescription mdescription
+	{- Avoid overwriting existing description with a default
+	 - description. -}
+	whenM (pure (isJust mdescription) <||> not . M.member u <$> uuidDescMap) $
+		describeUUID u =<< genDescription mdescription
 
 -- Everything except for uuid setup, shared clone setup, and initial
 -- description.

CHANGELOG

@@ -13,6 +13,9 @@ git-annex (7.20190508) UNRELEASED; urgency=medium
     import with such an expression will fail.
   * Improve shape of commit tree when importing from unversioned special
     remotes.
+  * init: When the repository already has a description, don't change it.
+  * describe: When run with no description parameter it used to set
+    the description to "", now it will error out.
 
  -- Joey Hess <id@joeyh.name>  Mon, 06 May 2019 13:52:02 -0400
 

Command/Describe.hs

@@ -21,7 +21,7 @@ seek :: CmdParams -> CommandSeek
 seek = withWords (commandAction . start)
 
 start :: [String] -> CommandStart
-start (name:description) = do
+start (name:description) | not (null description) = do
 	showStart' "describe" (Just name)
 	u <- Remote.nameToUUID name
 	next $ perform u $ unwords description

doc/bugs/git-annex-init_with_no_args_overwrites_existing_repo_description.mdwn

@@ -18,3 +18,5 @@ upgrade supported from repository versions: 0 1 2 3 4 5 6
 local repository version: 5
 (master_env_v135_py36) 13:47  [r2] $ uname -a
 Linux ip-172-31-90-58.ec2.internal 4.14.114-105.126.amzn2.x86_64 #1 SMP Tue May 7 02:26:40 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux
+
+> [[fixed|done]] --[[Joey]]

doc/bugs/git-annex-init_with_no_args_overwrites_existing_repo_description/comment_1_7facb84de8c8148e8f12ba2c4bd5c74b._comment

@@ -0,0 +1,16 @@
+[[!comment format=mdwn
+ username="joey"
+ subject="""comment 1"""
+ date="2019-05-23T16:40:50Z"
+ content="""
+Yikes, I was surprised to see this behavior. fixed for `init`.
+
+For `describe`, I see that when it's run with no parameter for the
+description, it sets the description to "". I suppose that's what you
+meant.
+
+I suppose something could conceivably depend on the current `git annex
+describe remote` behavior, but I checked and it's nowhere documented that
+describe with no description is allowed -- even the --help doesn't say that
+luckily. So I have also disallowed that.
+"""]]