travis.rb: sshkey upload fails with odd error message

I can generate a key and save it with travis sshkey --generate. However, when I attempt to reuse this key with another repository, I always seem to get this error message:

$ travis sshkey --upload ~/.ssh/id_travis_rsa"
password must be shorter than 1024 bytes
for a full error report, run travis report --pro

$ travis report --pro
System
Ruby:                     Ruby 2.4.0-p-1
Operating System:         Mac OS X 10.12
RubyGems:                 RubyGems 2.6.7

CLI
Version:                  1.8.2
Plugins:                  none
Auto-Completion:          yes
Last Version Check:       2016-10-20 17:29:15 -0500

Session
API Endpoint:             https://api.travis-ci.com/
Logged In:                as "westhomas"
Verify SSL:               yes
Enterprise:               no

Endpoints
org:                      https://api.travis-ci.org/ (access token)
pro:                      https://api.travis-ci.com/ (access token, current)

Last Exception
An error occurred running `travis sshkey --pro`:
    OpenSSL::OpenSSLError: password must be shorter than 1024 bytes
        from /Users/wes/.rvm/gems/ruby-head/gems/travis-1.8.2/lib/travis/tools/ssl_key.rb:21:in `initialize'
        from /Users/wes/.rvm/gems/ruby-head/gems/travis-1.8.2/lib/travis/tools/ssl_key.rb:21:in `new'
        from /Users/wes/.rvm/gems/ruby-head/gems/travis-1.8.2/lib/travis/tools/ssl_key.rb:21:in `has_passphrase?'
        from /Users/wes/.rvm/gems/ruby-head/gems/travis-1.8.2/lib/travis/cli/sshkey.rb:79:in `remove_passphrase'
        from /Users/wes/.rvm/gems/ruby-head/gems/travis-1.8.2/lib/travis/cli/sshkey.rb:38:in `update_key'
        from /Users/wes/.rvm/gems/ruby-head/gems/travis-1.8.2/lib/travis/cli/sshkey.rb:22:in `run'
        from /Users/wes/.rvm/gems/ruby-head/gems/travis-1.8.2/lib/travis/cli/command.rb:198:in `execute'
        from /Users/wes/.rvm/gems/ruby-head/gems/travis-1.8.2/lib/travis/cli.rb:64:in `run'
        from /Users/wes/.rvm/gems/ruby-head/gems/travis-1.8.2/bin/travis:18:in `<top (required)>'
        from /Users/wes/.rvm/gems/ruby-head/bin/travis:22:in `load'
        from /Users/wes/.rvm/gems/ruby-head/bin/travis:22:in `<main>'
        from /Users/wes/.rvm/gems/ruby-head/bin/ruby_executable_hooks:15:in `eval'
        from /Users/wes/.rvm/gems/ruby-head/bin/ruby_executable_hooks:15:in `<main>'

I can simply generate a new key for each repo, but this seems wrong.