PDF docs build: avoid spurious "warn" in build logs.
Improve on e4c886519 so that the string "warn" appears in
the output when there's a problem, and not when there isn't.
This should silence noise I've been seeing in my buildfarm
warning scraper.
Branch
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master
Details
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https://git.postgresql.org/pg/commitdiff/ecb8226af63dc8f1c0859977102764704368693b
Modified Files
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doc/src/sgml/Makefile | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)