fixing Confluence.remove_page_attachment_keep_version() method

[simonrupf]

Hi there,

TL;DR: This patch intends to fix the remove_page_attachment_keep_version() method in the Confluence class, so that it only removes (some) of the versions and not the attachment as a whole.

Background: I am faced with a Confluence instance that has been around for some years and for reasons™ had several hundreds of times the exact same versions of most of its attachments uploaded to it by a third party Confluence plugin, over and over again. In order to free up dozens of gigabytes of disk space, I am trying to use this library to iterate over the pages in a particular space and for each attachment found on these pages to delete all versions of the attachments except the most recent ones. The remove_page_attachment_keep_version() method seems to be intend to do just that.

Problem: When using the function with a given attachment and a number of versions to keep (m), it gets a list of all versions (n), then starts a while-loop deleting the version n-m of the attachment, until only m versions remain. Unfortunately the method Confluence.delete_attachment() seems to ignore the version parameter and always deletes the whole attachment. This causes an infinite loop, as it doesn't find the new version count, but gets a 403 error instead as the attachment isn't there anymore.

Partial solution: I noticed the Confluence.delete_attachment_by_id() function just below uses a different API call with an explicit version being required. Since we already have the attachment object including ID available in remove_page_attachment_keep_version() we can fix it by simply using that other deletion method.

Conclusion: This PR doesn't address the non-working version parameter in the Confluence.delete_attachment() method. I didn't touch it, as I don't know what other functionality may rely on it. Maybe it could be rewritten to use the Confluence.delete_attachment_by_id() when a version is provided and otherwise keep using the existing logic? Hope this PR serves to prevent others from deleting their attachments accidentally. Luckily we use testing instances. :-)

[gonchik]

Thanks, Good job!