Specifying multiple primary sources in top-level was deprecated in
Bundler 1.13.
As Bundler CLI uses primary source instead of global, "global source"
is replaced with "primary source".
Co-authored-by: David Rodríguez <deivid.rodriguez@riseup.net>
Signed-off-by: Takuya Noguchi <takninnovationresearch@gmail.com>
https://github.com/rubygems/rubygems/commit/1dd1753f6e