Only allow valid version overrides in bin stubs

This allows users to provide arguments like:

    rake _foo_

which cannot possibly match a version.  Previously RubyGems would give
a version parsing exception for such input.

Fixes #799

History.txt

@@ -22,6 +22,8 @@ Bug fixes:
   one or the other.  Pull request #795 by zebardy.
 * RubyGems can now use the bundler API against hosted gem servers in a
   directory.  Pull request #801 by Brian Fletcher.
+* RubyGems bin stubs now ignore non-versions.  This allows RubyGems bin stubs
+  to list file names like "_foo_".  Issue #799 by Postmodern.
 
 === 2.2.1 / 2014-01-06
 

lib/rubygems/installer.rb

@@ -641,7 +641,7 @@ def app_script_text(bin_file_name)
 if ARGV.first
   str = ARGV.first
   str = str.dup.force_encoding("BINARY") if str.respond_to? :force_encoding
-  if str =~ /\\A_(.*)_\\z/
+  if str =~ /\\A_(.*)_\\z/ and Gem::Version.correct?($1) then
     version = $1
     ARGV.shift
   end

test/rubygems/test_gem_installer.rb

@@ -41,7 +41,7 @@ def test_app_script_text
 if ARGV.first
   str = ARGV.first
   str = str.dup.force_encoding("BINARY") if str.respond_to? :force_encoding
-  if str =~ /\\A_(.*)_\\z/
+  if str =~ /\\A_(.*)_\\z/ and Gem::Version.correct?($1) then
     version = $1
     ARGV.shift
   end