Issue #10393 has been reported by Hideyuki Matsuyama.

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Bug #10393: String#start_with?の1.9.x非互換バグ
https://bugs.ruby-lang.org/issues/10393

* Author: Hideyuki Matsuyama
* Status: Open
* Priority: Normal
* Assignee: 
* Category: 
* Target version: 
* ruby -v: ruby 2.1.3p242 (2014-09-19 revision 47630) [x86_64-darwin13.0]
* Backport: 2.0.0: UNKNOWN, 2.1: UNKNOWN
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~~~
$ ruby -v
ruby 1.9.3p547 (2014-05-14 revision 45962) [x86_64-darwin13.4.0]
$ irb
> 'foo'.start_with? nil
 => false 
~~~
~~~
$ ruby -v
ruby 2.1.3p242 (2014-09-19 revision 47630) [x86_64-darwin13.0]
$ irb
> 'foo'.start_with? nil
TypeError: no implicit conversion of nil into String
~~~

バージョン1.9系との互換性を保つため、結果がfalseになることを期待します。



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