Calling Matcher.asBoolean() twice returns different results

There is one non-deterministic use case of using type coercion from java.util.regex.Matcher to a boolean. It was initially reported on Stack Overflow - https://stackoverflow.com/q/52930876/2194470

And here is an example that shows the problem:

def pattern = /[a-z]+/

def input = 'abc'

def matcher = input =~ pattern

println matcher as Boolean
println matcher as Boolean

Output:

true
false

Solution:

This problem can be solved by replacing matcher.find() with matcher.find(0), so casting matcher to a boolean does not modify search index and always starts from the beginning.

I will create a pull request in couple of minutes.