Metafont blows up in 2.3.9 build

[Matthias Neeracher]

2.3.9 does not build on MacOS X using the build recipe for 2.3.8:

mf feta-braces-f.mf
This is METAFONT, Version 2.7182 (Web2C 7.4.5)
(feta-braces-f.mf (feta-beugel.mf (feta-autometric.mf
******************************************************
Using feta Autometric macros. 
Do not worry about the @ signs in the output, they are not errors. 
******************************************************) (feta-macros.mf)
(feta-params.mf)
@{font@:GNU@:LilyPond@:feta-braces-f@:90@:address@hidden
brace number 0
@{char@:brace number 0@:0@:0@:5.86842@:44.01317@:44.01317@:5.86842@:0@:braceA@:
address@hidden [0]

[...]

brace number 38
@{char@:brace number 38@:38@:0@:7.55402@:56.65508@:56.65508@:7.55402@:0@:braceA
BM@:address@hidden [38]
Resolution and/or magnification is too high
>> error.please.report
! Isolated expression.
<to be read again> 
:
<for(39)> ...ion is too high";error.please.report:

<address@hidden>;fi...
<for(5)> ...raw_brace(y,x,linethickness);fi.endfor
; ENDFOR
l.111 endfor


? x
Output written on feta-braces-f.2602gf (39 characters, 400428 bytes).
Transcript written on feta-braces-f.log.
gnumake: *** [out/feta-braces-f.log] Error 1

Is this an issue that occurs on other platforms as well, or should I investigate this as a platform specific bug?

Thanks
Matthias