Description:
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The method call \ResourceBundle::getLocales('') from the intl extensions returns a huge array with language codes.

The list contains (German names here):

'nb'    => 'Norwegisch Bokmål'
'nb_NO' => 'Norwegisch Bokmål (Norwegen)'
'nb_SJ' => 'Norwegisch Bokmål (Spitzbergen und Jan Mayen)'
'nn'    => 'Norwegisch Nynorsk'
'nn_NO' => 'Norwegisch Nynorsk (Norwegen)'

but *NOT* the main key 'no' => 'Norwegisch'

Using 'no' however works and translates (to 'Norwegisch') without a problem.

Problem occurs on Windows and Linux with all current php versions (7.1, 7.2, 7.3, 7.4RC1).

Test script:
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a) With intl extension NOT enabled
Windows shell / cmd:
php -dextension=php_intl.dll -r "var_dump(\ResourceBundle::getLocales(''));" | find "no"

Linux:
php -dextension=intl.so -r "var_dump(\ResourceBundle::getLocales(''));" | grep no

b) With intl extension enabled
Windows shell / cmd:
php -r "var_dump(\ResourceBundle::getLocales(''));" | find "no"

Linux:
php -r "var_dump(\ResourceBundle::getLocales(''));" | grep no


Expected result:
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'no' should be a key in the array returned by:
\ResourceBundle::getLocales('')

Test scripts (above) should output the 'no' key.

Actual result:
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Key does not exist in array returned by:
\ResourceBundle::getLocales('')