Added a comment

doc/bugs/Glacier_remote_uploads_duplicates/comment_5_6980a912d3582c2f2511e4827e9e76b3._comment

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+[[!comment format=mdwn
+ username="http://joeyh.name/"
+ nickname="joey"
+ subject="comment 5"
+ date="2013-05-29T17:54:11Z"
+ content="""
+I started to make a branch with the change I suggested, but then I had another idea.
+
+The checkpresent hook can return either True or, False, or fail with a message if it cannot successfully check the remote. Currently for glacier, when --trust-glacier is not set, it always returns False. Crucially, in the case when a file is in glacier, this is telling git-annex it's not there, so copy re-uploads it. What if it instead, when the glacier inventory is missing a file, it returns False. And when the glacier inventory has a file, unless --trust-glacier is set, it *fails*.
+
+The result would be:
+
+* `git annex copy --to glacier` would only send things not listed in inventory. If a file is listed in the inventory, `copy`
+  would complain that --trust-glacier` is not set, and not re-upload the file.
+* `git annex drop` would only trust that glacier has a file when --trust-glacier is set. Behavior unchanged.
+* `git annex move --to glacier`, when the file is not listed in inventory, would send the file, and delete it locally. Behavior unchanged.
+* `git annex move --to glacier`, when the file is listed in inventory, would only trust that glacier has the file when --trust-glacier is set
+* `git annex copy --from glacier` / `git annex get`, when the file is located in glacier, would trust the location log, and attempt to get the file from glacier.
+
+This seems like it should do the right thing in all cases, but I have not tested it. I've pushed a `glacier` branch with this change.
+"""]]