looks like a font matching bug...
Symbol                               Type 1       no  no  no    1598  0 file:
/usr/share/fonts/truetype/ttf-bitstream-vera/Vera.ttf

Should be fixed by adding the following to the URW section of /etc/fonts/fonts.conf.

        <alias>
          <family>Symbol</family>
          <accept><family>Standard Symbols L</family></accept>
        </alias>

i.e. fc-match --sort "Symbol"; should give 's050000l.pfb: "Standard Symbols L"
"Regular"' as the top match.

Also, as per http://freedesktop.org/wiki/Software/poppler there should be an
alias from ZapfDingbats to Dingbats. 

The Ubuntu fontconfig has the aliases from
http://freedesktop.org/wiki/Software/poppler for zaftdingbats and symbol

$ fc-match --sort "Symbol";
DejaVuSans.ttf: "DejaVu Sans" "Book"
Vera.ttf: "Bitstream Vera Sans" "Roman"
n019003l.pfb: "Nimbus Sans L" "Regular"
... a pile of other fonts listed ...
d050000l.pfb: "Dingbats" "Regular"
s050000l.pfb: "Standard Symbols L" "Regular"

So why then does fontconfig give 'DejaVuSans.ttf: "DejaVu Sans" "Book"' as the
first font? We are sort of trusting fontconfig to give a sane result...

Reassigning to fontconfig. At the moment the prefer symbols fonts is not a
Symbols one, the default fonts.conf should probably have a :

"
	<match target="pattern">
		<test name="family">
			<string>Symbol</string>
		</test>
		<edit name="family" mode="prepend" binding="same">
			<string>Standard Symbols L</string>
		</edit>
	</match>
"

Created attachment 5296 [details] [review]
Prefer "Standard Symbols L" as Symbol font

I've added Standard Symbols L as a standard alias for Symbol.  keithp says that
it's wrong to prefer the URW font over the real Symbol font.

The alias is not enough. As explained by previous comments the fonts.conf
already has the aliases described by
http://freedesktop.org/wiki/Software/poppler (you could list the "Dingbats" one
too) but Symbol is still not the preferred choice

It's probably a language issue, and making the alias binding strong instead of
weak will override that. Don't prepend it to the list though, just append with
strong binding.

I've committed the strong match binding.

We still need an alias from ZapfDingbats to Dingbats.

$ fc-match ZapfDingbats
DejaVuSans.ttf: "DejaVu Sans" "Book"

$ fc-match Dingbats
d050000l.pfb: "Dingbats" "Regular"

Right now poppler is affected by this problem when rendering documents with forms.