multiple -m second try

Test suite passes this time. When committing the adjusted branch, use
the old method to make a message that old git-annex can consume. Also
made the code accept the new message, so that eventually
commitTreeExactMessage can be removed.

Sponsored-by: Kevin Mueller on Patreon

doc/git-annex-assist.mdwn

@@ -34,6 +34,9 @@ files that it does not match will instead be added with `git add`.
 
   Use this option to specify a commit message.
 
+  If multiple -m options are given, their values are concatenated
+  as separate paragraphs.
+
 * `--content-of=path` `-C path`
 
   Only add, pull, and push files in the given path.

doc/git-annex-import.mdwn

@@ -107,6 +107,9 @@ the tree of files on the remote, even when importing into a subdirectory.
   Use this option to specify a commit message for the changes that have
   been made to the special remote since the last import from it.
 
+  If multiple -m options are given, their values are concatenated
+  as separate paragraphs.
+
 # IMPORTING FROM A DIRECTORY
 
 When run with a path, `git annex import` **moves** files from somewhere outside

doc/git-annex-sync.mdwn

@@ -51,6 +51,9 @@ when syncing with repositories that have preferred content configured.
 
   Use this option to specify a commit message.
 
+  If multiple -m options are given, their values are concatenated
+  as separate paragraphs.
+
 * `--pull`, `--no-pull`
 
   Use this option to disable pulling.

doc/todo/multiple_-m.mdwn

@@ -1,6 +1,4 @@
 git-annex sync etc -m should be able to be specified multiple times. In git
 commit, multiple -m can be used to make a multiparagraph commit. --[[Joey]]
 
-> I got this implemented, but it caused a reversion. See 
-> [[!commit a8dd85ea5a9f8515819db04b9f1d154488193e7d]]
-> for what needs to be done on this next. --[[Joey]]
+> [[done]]