Use separate labels for the Save/Publish button when you are creating a new page vs saving changes to an existing page.
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I could have sworn this was "Submit changes" (for existing pages) and "Save page" (when creating pages) on non-VE en.wp two weeks ago, but indeed it is both "Save Page" ("savearticle")...
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I did this in 347ec3352801cae78c3c057c2748fe44129c113b back in June 2016, and it went out in MediaWiki 1.28.