Inconsistency of jessie-backports

Hello,

It seem that I discovered some inconsistency of debian jessie-backports 
repository, contents of the main/source/Sources.bz2 and 
non-free/source/Sources.bz2 differs from it's xz and gz versions.
Simple script to check this issue:
MIRROR="$1"

echo Sources checksums
echo -n "bz2 - "; wget -q 
http://${MIRROR}/debian/dists/jessie-backports/main/source/Sources.bz2 
-O - | md5sum ;
echo -n "gz - "; wget -q 
http://${MIRROR}/debian/dists/jessie-backports/main/source/Sources.gz -O 
- | md5sum
echo -n "xz - "; wget -q 
http://${MIRROR}/debian/dists/jessie-backports/main/source/Sources.xz -O 
- | md5sum;

echo Checksums from Release file
wget -q http://${MIRROR}/debian/dists/jessie-backports/Release -O - | 
grep -Pi "\s+[0-9a-f]{32}\s+[0-9]*\s+main/source/Sources(.bz2|.xz|.gz)?$"

echo Checksums of unpacked contents
echo -n "bz2 - "; wget -q 
http://${MIRROR}/debian/dists/jessie-backports/main/source/Sources.bz2 
-O - | bunzip2 -c | md5sum;
echo -n "gz - "; wget -q 
http://${MIRROR}/debian/dists/jessie-backports/main/source/Sources.gz -O 
- | gunzip -c | md5sum
echo -n "xz - "; wget -q 
http://${MIRROR}/debian/dists/jessie-backports/main/source/Sources.xz -O 
- | unxz -c | md5sum;

Currently I'm getting following output on majority of mirrors (tested on 
ftp.de.debian.org, ftp.nl.debian.org, mirror.yandex.ru/debian):
# ./check.sh ftp.debian.org

Sources checksums
bz2 - c19744f3ac05ddfade3222c52f10499d  -    # <-- bz2 file checksum 
matches to checksum mentioned in signed Release file
gz - 89b8e6530a1c2295cf880f4163ec8a1b  -
xz - 3a7010633cff5762770a9677f2f150d5  -

Checksums from Release file
  30e4f8820c1c29e34bce3f9c0061b9ef   867335 main/source/Sources
  c19744f3ac05ddfade3222c52f10499d   146904 main/source/Sources.bz2 # <--
  89b8e6530a1c2295cf880f4163ec8a1b   190243 main/source/Sources.gz
  3a7010633cff5762770a9677f2f150d5   153388 main/source/Sources.xz

Checksums of unpacked contents
bz2 - 2f4b1d84556c5e5e7c758b50f01ec5c6  -   # <-- unpacked bz2 file 
differs and it's checksum is wrong
gz - 30e4f8820c1c29e34bce3f9c0061b9ef  -
xz - 30e4f8820c1c29e34bce3f9c0061b9ef  -