I have a git job that builds all branches except master. I have the job setup to send email to only the committers using email-ext. The idea being that developers can push their branches to the CI server and then get feedback on if all tests work in the production environment. When a new branch is pushed to the server the build runs and no emails are sent. I'm using version 1.1.19 of the bit plugin, a 2.22 debug version of the email-ext plugin on Jenkins version 1.470. The debug output from the email-ext plugin shows:
20:43:27 [WARNINGS] Parsing warnings in console log with parser Java Compiler (javac)
20:43:27 Archiving artifacts
20:43:29 Publishing Cobertura coverage report...
20:43:29 Publishing Cobertura coverage results...
20:43:34 Recording test results
20:43:35 Description set: Branch origin/feature.create-tournament-on-import
20:43:36 Email was triggered for: Success
20:43:36 Sending email for trigger: Success
20:43:36 Send to developers
20:43:36 Getting users from changeset
20:43:36 Get users from changeset - users.size() = 0
20:43:36 413: recipientAddresses.size() = 0
20:43:36 Setting 0 recipients
20:43:36 An attempt to send an e-mail to empty list of recipients, ignored.
20:43:36 Finished: SUCCESS

The changeset in Jenkins is indeed empty, although I would think this should show the changes from master or where the branch was created.