How do I ignore a module .git directory? I've got a Drupal 8 installation that I manage with Drush 8.1.2, with nothing in that installation in Git except a custom module I am writing (module directory = location of .git directory = /sites/all/modules/mymodulename).

Whenever I do a drush pm-update it complains about my module:


  Project was not packaged by drupal.org but obtained from git. You need to enable git_deploy module


I don't see how I can follow the suggestion of git_deploy which, as far as I can tell, provides an update source for modules checked out of drupal.org... so how can I let Drush know that my module is a stand-alone Git installation, and stop it from generating that warning every time?

The --lock option to drush pm-update is probably not appropriate, since my module is neither a core or a contrib module, and it doesn't change the warning in any case.  The only thing I've found to make that warning go away is to delete or rename the module's .git directory.

p.s., one thing I noticed later: the warning also goes away if the module is uninstalled: probably because uninstalled modules aren't checked for upgrades.
Your analysis is correct; git_deploy is only useful for projects that are ultimately hosted on drupal.org.  The pm-* commands only operate on drupal.org projects, and have no facility for ignoring projects from other sources.  This is a limitation of Drush; improvements in this area would be welcome.