I have set up packer to install automatically and install from site for version: Packer 0.6.1 linux (amd64). However every time I run a job that uses packer, I get this error:
Unpacking http://dl.bintray.com/mitchellh/packer/:0.6.1_linux_amd64.zip to .....
FATAL: Execution failed:
Finished: FAILURE
Build step 'Packer' marked build as failure

Notice the colon in the URL. I guess the reason behind it is that when the crawler (https://github.com/jenkinsci/backend-crawler/blob/master/packer.groovy) is crawling href tags, the tags contain a colon which is never removed by the crawler.

So I think the problem is with the crawler and not with the plugin.