It never has.
My Cuban-born uncle went to his oral exam for U.S. citizenship in Miami back around 1967 dressed in his U.S. Army uniform that included his Green Beret, the Combat Infantryman Badge, the Vietnam Service Ribbon with two clusters, the Bronze Star with Combat "V" ribbon with two clusters and the Purple Heart ribbon with two clusters. The right sleeve of his uniform was empty as his right arm was still strapped to his chest as a result of the rounds he had taken to his right shoulder a few weeks before in Vietnam.
When we asked him what questions he had been asked in his oral exam, he said,
"The examiner did not ask me a single question. He just looked at me, up and down a couple of times, and said, 'You passed.'".
For earlier historical examples, look up "Irish Brigade" and "Eleventh Corps, Army of the Potomac".
Passed with flying colors I'd say!