Downloading custom module with drush make
Add a line to the make file to make it look like so:

core = 7.x
api = 2
projects[cs_all][type] = "module"
projects[cs_all][subdir] = "contrib"
projects[cs_all][download][url] = "git@bitbucket.org:myrepo/cs_all.git"
projects[cs_all][download][type] = "git"
projects[cs_all][download][branch] = "master"


So add the line to indicate 'type = git' . That would make it look closer to what is documented on https://www.drupal.org/node/1432374 ...

Curious to hear what results you'd get then.