bug#21257: auto-mode-alist too eager for Ruby?

[David Kastrup]

I just got a temporary file created for a Git commit message with the
name "/tmp/tmp3djbru" and Emacs decided to throw the buffer in Ruby
mode.  Seriously?

The respective entry in auto-mode-alist appears to be

 
("\\(?:\\.rb\\|ru\\|rake\\|thor\\|jbuilder\\|rabl\\|gemspec\\|podspec\\|/\\(?:Gem\\|Rake\\|Cap\\|Thor\\|Puppet\\|Berks\\|Vagrant\\|Guard\\|Pod\\)file\\)\\'"
 . ruby-mode)

which appears to admit a whole lot of files just based on the ending
letters without any distinguishing symbols before them.

-- 
David Kastrup