I added some comments to #885312 about a related issue
with missing jsmath fonts, and suggested that python-matplotlib
probably could also be patched to not "consider" the fonts
missing in fedora.

StixGeneral is how the fonts were organised in the previous version, it's now deprecated for the font split Fedora installs. Moreover we do install the correct fontconfig aliasing rules so STIXGeneral is aliased to the new fonts

$ fc-match STIXGeneral
STIX-Regular.otf: "STIX" "Regular"

Therefore your software has two different bugs:

1. it has not been fixed to work with the new STIX split
2. it does not respect fontconfig aliasing

You should get this fixed upstream. But it's not a Fedora STIX package bug

Ok. I am not an fonts specialist... It works in f17 but not rawhide:

In f17 I see this:
--%<---%<--%<---%<--%<---%<--%<---%<--%<---%<--%<---%<--%<---%<--%<---%<--%<---%<
$ rpm -q python-matplotlib
python-matplotlib-1.2.0-5.fc17.x86_64
$ rpm -qa | grep stix
stix-fonts-1.0.0-3.fc17.noarch
$ fc-match STIXGeneral
STIXGeneral.otf: "STIXGeneral" "Regular"
$ fc-list | grep -i stix
STIXGeneral:style=Bold
STIXGeneral:style=Italic
STIXGeneral:style=Regular
STIXGeneral:style=Bold Italic
$ sage -t  -force_lib "devel/sage/sage/geometry/cone.py"      
sage -t -force_lib "devel/sage/sage/geometry/cone.py"       
         [5.7 s]
 
----------------------------------------------------------------------
All tests passed!
Total time for all tests: 5.7 seconds
--%<---%<--%<---%<--%<---%<--%<---%<--%<---%<--%<---%<--%<---%<--%<---%<--%<---%<


And in rawhide:
--%<---%<--%<---%<--%<---%<--%<---%<--%<---%<--%<---%<--%<---%<--%<---%<--%<---%<
$ rpm -q python-matplotlib
python-matplotlib-1.2.0-5.fc19.x86_64
$ rpm -qa | grep stix
stix-math-fonts-1.1.0-3.fc19.noarch
stix-fonts-1.1.0-3.fc19.noarch
$ fc-match STIXGeneral
Fontconfig warning: "/etc/fonts/conf.d/50-user.conf", line 9: reading configurations from ~/.fonts.conf is deprecated.
STIX-Regular.otf: "STIX" "Regular"
$ fc-list | grep -i stix
Fontconfig warning: "/etc/fonts/conf.d/50-user.conf", line 9: reading configurations from ~/.fonts.conf is deprecated.
/usr/share/fonts/stix/STIX-Regular.otf: STIX:style=Regular
/usr/share/fonts/stix/STIX-Italic.otf: STIX:style=Italic
/usr/share/fonts/stix/STIX-Bold.otf: STIX:style=Bold
/usr/share/fonts/stix/STIX-BoldItalic.otf: STIX:style=Bold Italic
/usr/share/fonts/stix/STIXMath-Regular.otf: STIX Math:style=Regular
$ sage -t  -force_lib "devel/sage/sage/geometry/cone.py"
sage -t -force_lib "devel/sage/sage/geometry/cone.py"       
**********************************************************************
File "/usr/lib64/sagemath/devel/sage/sage/geometry/cone.py", line 930:
    sage: quadrant.plot()
Expected nothing
Got:
    doctest:1214: UserWarning: findfont: Font family ['STIXGeneral'] not found. Falling back to Bitstream Vera Sans
    doctest:1214: UserWarning: findfont: Font family ['STIXSizeOneSym'] not found. Falling back to Bitstream Vera Sans
    doctest:1214: UserWarning: findfont: Font family ['STIXSizeThreeSym'] not found. Falling back to Bitstream Vera Sans
    doctest:1214: UserWarning: findfont: Font family ['STIXSizeFourSym'] not found. Falling back to Bitstream Vera Sans
    doctest:1214: UserWarning: findfont: Font family ['STIXSizeFiveSym'] not found. Falling back to Bitstream Vera Sans
    doctest:1214: UserWarning: findfont: Font family ['STIXSizeTwoSym'] not found. Falling back to Bitstream Vera Sans
    doctest:1214: UserWarning: findfont: Font family ['STIXNonUnicode'] not found. Falling back to Bitstream Vera Sans
    doctest:1214: UserWarning: findfont: Font family ['cmb10'] not found. Falling back to Bitstream Vera Sans
    doctest:1214: UserWarning: findfont: Font family ['cmtt10'] not found. Falling back to Bitstream Vera Sans
    doctest:1214: UserWarning: findfont: Font family ['cmss10'] not found. Falling back to Bitstream Vera Sans
    <BLANKLINE>
**********************************************************************
1 items had failures:
   1 of   5 in __main__.example_17
***Test Failed*** 1 failures.
For whitespace errors, see the file /home/pcpa/.sage/tmp/cone_4295.py
         [5.8 s]
 
----------------------------------------------------------------------
The following tests failed:


        sage -t -force_lib "devel/sage/sage/geometry/cone.py"
Total time for all tests: 5.9 seconds
--%<---%<--%<---%<--%<---%<--%<---%<--%<---%<--%<---%<--%<---%<--%<---%<--%<---%<

Note that I have backported several f18/rawhide packages to f17 in
http://pcpa.fedorapeople.org/sagemath/f17/ and opened the bug report
to somehow try to get some hints on how to address the problem :-)
I see that %{python_sitearch}/matplotlib/font_manager.py does a
popen call to fc-list to find fonts, example in f17:

$ fc-list STIXGeneral
STIXGeneral:style=Bold
STIXGeneral:style=Italic
STIXGeneral:style=Regular
STIXGeneral:style=Bold Italic

but rawhide returns nothing for the same command. Is it expected?

This is a terrible way to use fontconfig, you need to link to the fontconfig library and evaluate fontconfig patterns every time you need to print a string, not do a few calls on fixed font names and hope the font coverage is suitable. Your upstream is trying to handle fontconfig the way it handled pre-fontconfig pre-unicode font management (which was no management at all, but reliance on small limited pre-known lists of fonts that never changed properties). That is never going to work properly now that fontconfig has been there for a decade, all major *nix software uses it properly, and fonts change a lot faster than before as a result.

(and usually you do *not* want to call fontconfig direcly, you use pango-cairo or another smart library that does the fontconfig heavy lifting and glyph shaping for you)

fc-list and fc-match are there mainly for debugging purposes, calling them directly can not simulate full fontconfig support and breaks as soon as fonts change (as seen there)

Lastly, fc-list lists installed fonts, fc-match finds the closest installed font, this is only the same thing when you happen to hit the font you requested directly.

PS You can also tell your upstream that every major distribution has been shipping DejaVu instead of Bistream Vera for at least five years.

(In reply to comment #3)
> Ok. I am not an fonts specialist... It works in f17 but not rawhide:

I cut and pasted fc-match output from a rawhide system with rawhide font packages

(In reply to comment #4)
> This is a terrible way to use fontconfig, you need to link to the fontconfig
> library and evaluate fontconfig patterns every time you need to print a
> string, not do a few calls on fixed font names and hope the font coverage is
> suitable.

Thanks. I made a simple hack patch (functionally making things
work if conditionally applied to f18 and rawhide) removing/renaming
patterns, but that clearly looks wrong, and asked for help and
information at
http://sourceforge.net/mailarchive/message.php?msg_id=30202451

python-matplotlib-1.2.0-7.fc18 has been submitted as an update for Fedora 18.
https://admin.fedoraproject.org/updates/python-matplotlib-1.2.0-7.fc18