Mark private notes more clearly (#16240).

Contributed by Jan Schulz-Hofen.

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extra : convert_revision : svn%3Ae93f8b46-1217-0410-a6f0-8f06a7374b81/trunk%4013367
pdf: add test to export issue pdf with UTF-8 U+FFFD (#17826)

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extra : convert_revision : svn%3Ae93f8b46-1217-0410-a6f0-8f06a7374b81/trunk%4013368
pdf: fix r13368 test name (#17826)

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extra : convert_revision : svn%3Ae93f8b46-1217-0410-a6f0-8f06a7374b81/trunk%4013369