prevent unnecessary updates for brew casks with version "latest"

[pjungermann]

prevent unnecessary updates for brew casks with version "latest"

[pjungermann]

dropbox seems to have a version at the DMG file (but not exposed at brew cask), but not inside the download URL used at the brew cask. Also, he install/upgrade process identifies it as already downloaded.

==> Upgrading 1 outdated package:
dropbox latest -> latest
==> Upgrading dropbox
==> Satisfying dependencies
==> Downloading https://www.dropbox.com/download?plat=mac&full=1
Already downloaded: {home_folder}/Library/Caches/Homebrew/downloads/2c8afbdc56eb2cb1170f526424b46e25565b9acf4fecaa19b4b294cf1b3e9a7d--Dropbox 77.4.131.dmg
==> No SHA-256 checksum defined for Cask 'dropbox', skipping verification.
==> Removing launchctl service com.dropbox.DropboxMacUpdate.agent
Password:
==> Backing App 'Dropbox.app' up to '/usr/local/Caskroom/dropbox/latest/Dropbox.
==> Removing App '/Applications/Dropbox.app'.
hdiutil attach -plist -nobrowse -readonly -noidme -mountrandom /var/folders/c8/8jrjfc6d537g8f34_mrtr4b5j12725/T/d20191023-55680-7s0zmr {home_folder}/Library/Caches/Homebrew/downloads/2c8afbdc56eb2cb1170f526424b46e25565b9acf4fecaa19b4b294cf1b3e9a7d--Dropbox\ 77.4.131.dmg
mkbom -s -i /var/folders/c8/8jrjfc6d537g8f34_mrtr4b5j12725/T/20191023-55680-1pmui3j.list -- /var/folders/c8/8jrjfc6d537g8f34_mrtr4b5j12725/T/20191023-55680-1502t44.bom
ditto --bom /var/folders/c8/8jrjfc6d537g8f34_mrtr4b5j12725/T/20191023-55680-1502t44.bom -- /private/var/folders/c8/8jrjfc6d537g8f34_mrtr4b5j12725/T/d20191023-55680-7s0zmr/dmg.A2bS8u /var/folders/c8/8jrjfc6d537g8f34_mrtr4b5j12725/T/d20191023-55680-cpom3s
diskutil eject /private/var/folders/c8/8jrjfc6d537g8f34_mrtr4b5j12725/T/d20191023-55680-7s0zmr/dmg.A2bS8u
cp -pR /var/folders/c8/8jrjfc6d537g8f34_mrtr4b5j12725/T/d20191023-55680-cpom3s/.dbx_preinstall /usr/local/Caskroom/dropbox/latest/.dbx_preinstall
cp -pR /var/folders/c8/8jrjfc6d537g8f34_mrtr4b5j12725/T/d20191023-55680-cpom3s/Dropbox.app/. /usr/local/Caskroom/dropbox/latest/Dropbox.app
cp -pR /var/folders/c8/8jrjfc6d537g8f34_mrtr4b5j12725/T/d20191023-55680-cpom3s/.dbx_install /usr/local/Caskroom/dropbox/latest/.dbx_install
chmod -Rf +w /var/folders/c8/8jrjfc6d537g8f34_mrtr4b5j12725/T/d20191023-55680-cpom3s
==> Moving App 'Dropbox.app' to '/Applications/Dropbox.app'.
==> Purging files for version latest of Cask dropbox
🍺  dropbox was successfully upgraded!
upgraded dropbox

spotify has no version number in the DMG file, but is similar besides that (generic download URL, ...).

[pjungermann]

recheck after resolving issue #8

[pjungermann]

With the use of the outdated boolean flag at the brew info --json=v2 {formula} output which considers auto-updated software as not outdated, this is considered solved.