Strange error when importing pylab

Hi,

I have a strange error while importing pylab in parallel to my own
library. In the test script below, my function open_spec (which has
strictly nothing to do w/ pylab: it's a swig wrapper to a C-library of
mine) doesn't act the same if I import pylab first or not:

···

----
#!/usr/bin/env python

import sys
import IFU_py_io as IFU # IFU_C_iolibs wrapper

IFU.set_user_dataformat()
spec = IFU.SPECTRUM()

for specName in sys.argv[1:]: # Loop over spectra
    print "BEFORE pylab:", specName,
    IFU.open_spec(spec,specName,"i")
    print "(%d px, start=%.2f, step=%.2f)" % (spec.npts,spec.start,spec.step)

import pylab # Matplotlib

for specName in sys.argv[1:]: # Loop over spectra
    print "AFTER pylab:", specName,
    IFU.open_spec(spec,specName,"i")
    print "(%d px, start=%.2f, step=%.2f)" % (spec.npts,spec.start,spec.step)
----

The output result is:

BEFORE pylab: spec_113_C05_081_033_B.fits (1177 px, start=3200.00, step=2.38)
AFTER pylab: spec_113_C05_081_033_B.fits (1177 px, start=1.00, step=1.00)

while absolutely no pylab function is used in the IFU package...

Do you have an idea of what could happen?

Cheers.
--
   .~. Yannick COPIN (o:>* Doctus cum libro
   /V\ Institut de physique nucleaire de Lyon (IN2P3 - France)
  // \\ Tel: (33/0) 472 431 968 AIM: YnCopin ICQ: 236931013
/( )\ http://snovae.in2p3.fr/ycopin/
  ^`~'^

--
   .~. Yannick COPIN (o:>* Doctus cum libro
   /V\ Institut de physique nucleaire de Lyon (IN2P3 - France)
  // \\ Tel: (33/0) 472 431 968 AIM: YnCopin ICQ: 236931013
/( )\ http://snovae.in2p3.fr/ycopin/
  ^`~'^