When backing up repositories using an auth token and https, the GitHub personal auth token is leaked in each backed up repository. It is included in the URL of each repository's git remote url.
This is not needed as they are public and can be accessed without the token and can cause issues in the future if the token is ever changed, so I think it makes more sense not to have the token stored in each repo backup. I think the token should only be "leaked" like this out of necessity, e.g. it's a private repository and the --prefer-ssh option was not chosen so https with auth token was required to perform the clone.
Currently the script puts all release assets into the same folder called `releases`. So any time 2 release files have the same name, only the last one downloaded is actually saved. A particularly bad example of this is MacDownApp/macdown where all of their releases are named `MacDown.app.zip`. So even though they have 36 releases and all 36 are downloaded, only the last one is actually saved.
With this change, each releases' assets are now stored in a fubfolder inside `releases` named after the release name. There could still be edge cases if two releases have the same name, but this is still much safer tha the previous behavior.
This change also now checks if the asset file already exists on disk and skips downloading it. This drastically speeds up addiotnal syncs as it no longer downloads every single release every single time. It will now only download new releases which I believe is the expected behavior.
closes https://github.com/josegonzalez/python-github-backup/issues/126
Found out that the flag "--skip-existing" did not work out as expected on Python
3.6. Tracked it down to the comparison which has to be against a string of bytes
in Python3.
Keychain arguments are only supported on Mac OSX.
Added check for operating system so we give a
"Keychain arguments are only supported on Mac OSX"
error message rather than a "No password item matching the
provided name and account could be found in the osx keychain"
error message
This avoids the backup output having lots of "[new branch]" messages
because removing the old remote name removed all of the existing branch
references.
