Bug#890887: babl FTBFS on s390x: FAIL: float-to-8bit

[Adrian Bunk]

Source: babl
Version: 0.1.44-1
Severity: serious

https://buildd.debian.org/status/fetch.php?pkg=babl&arch=s390x&ver=0.1.44-1&stamp=1519101395&raw=0

...
FAIL: float-to-8bit
===================

Missing fast-path babl conversion detected, Implementing missing babl fast paths
accelerates GEGL, GIMP and other software using babl, warnings are printed on
first occurance of formats used where a conversion has to be synthesized
programmatically by babl based on format description

*WARNING* missing babl fast path(s): "R'G'B'A float" to "R'G'B'A u8"
 float -> u8 5 failed #2[1]  got 255 expected 156
	" 0x148fa36b0 0x148f9c4d0 1"	-1579716768	BablFishPath
		cost:1783.000000 error:0.000000000000
	"../extensions/.libs/float.so 0: RaGaBaA float to R'aG'aB'aA float"	0	BablConversionLinear
		pixels:0
		error: 0.000000
	"../extensions/.libs/gegl-fixups.so 0: R'aG'aB'aA float to R'G'B'A float"	0	BablConversionLinear
		pixels:0
		error: 0.000000
	"../extensions/.libs/simple.so 0: R'G'B'A float to R'G'B'A u8"	0	BablConversionLinear
		pixels:0
		error: 0.000000
 float -> u8 5 failed #2[2]  got 255 expected 213
	" 0x148fa36b0 0x148f9c4d0 1"	-1579716768	BablFishPath
		cost:1783.000000 error:0.000000000000
	"../extensions/.libs/float.so 0: RaGaBaA float to R'aG'aB'aA float"	0	BablConversionLinear
		pixels:0
		error: 0.000000
	"../extensions/.libs/gegl-fixups.so 0: R'aG'aB'aA float to R'G'B'A float"	0	BablConversionLinear
		pixels:0
		error: 0.000000
	"../extensions/.libs/simple.so 0: R'G'B'A float to R'G'B'A u8"	0	BablConversionLinear
		pixels:0
		error: 0.000000
FAIL float-to-8bit (exit status: 1)

============================================================================
Testsuite summary for babl 0.1.44
============================================================================
# TOTAL: 23
# PASS:  22
# SKIP:  0
# XFAIL: 0
# FAIL:  1
# XPASS: 0
# ERROR: 0
============================================================================
See tests/test-suite.log
============================================================================
make[4]: *** [Makefile:973: test-suite.log] Error 1