Citeproc: Require a digit for an implicit "page" locator...

inside explicit locator syntax `{...}`.

Previously a locator specified as `{}` would be rendered
as `p.` with nothing after it.

Closes #8288.

src/Text/Pandoc/Citeproc/Locator.hs

@@ -80,9 +80,9 @@ pLocatorDelimited locMap = try $ do
 
 pLocatorLabelDelimited :: LocatorMap -> LocatorParser (Text, Text, Bool)
 pLocatorLabelDelimited locMap
-  = pLocatorLabel' locMap lim <|> return ("", "page", True)
-    where
-        lim = stringify <$> anyToken
+  = pLocatorLabel' locMap (stringify <$> anyToken)
+      <|> (("", "page", True) <$ lookAhead (pMatchChar "digit" isDigit))
+      <|> (pure ("", "", True))
 
 pLocatorIntegrated :: LocatorMap -> LocatorParser LocatorInfo
 pLocatorIntegrated locMap = try $ do

test/command/pandoc-citeproc-locators-delimited.md

@@ -100,7 +100,7 @@ Unbalanced curly } ends early[^18]
 
 [^6]: Subsequent, p. {(a)}.
 
-[^7]: Ibid-with-locator.
+[^7]: Ibid.
 
 [^8]: Ibid 123-35 numbers are suffix.