bug#29076: GTK+ 'icon-theme.cache' files are not reproducible

[Ludovic Courtès]

Here’s an example:

--8<---------------cut here---------------start------------->8---
$ wget -q -O - 
https://mirror.hydra.gnu.org/guix/nar/gzip/7drfxfiwif436bw908iy6jm3myrinn4m-xfce4-session-4.12.0
 | gunzip -c | guix archive -x xfsession1
$ wget -q -O -   
https://berlin.guixsd.org/nar/gzip/7drfxfiwif436bw908iy6jm3myrinn4m-xfce4-session-4.12.0
 | gunzip | guix archive -x xfsession2
$ diff -ru --no-dereference xfsession[12]
Ciferecaj dosieroj xfsession1/share/icons/hicolor/icon-theme.cache kaj 
xfsession2/share/icons/hicolor/icon-theme.cache estas malsamaj
$ diffoscope xfsession[12]/share/icons/hicolor/icon-theme.cache
--- xfsession1/share/icons/hicolor/icon-theme.cache
+++ xfsession2/share/icons/hicolor/icon-theme.cache
│┄ xxd not available in path. Falling back to Python hexlify.
│┄ 'showttf' not available in path. Falling back to binary comparison.
@@ -1,20 +1,20 @@
 000100000000000c000002380000000b0000003cffffffff000000a0ffffffff
 ffffffffffffffff000000ec000001140000016cffffffff000001bc00000068
 000000480000005c73797374656d2d68696265726e6174650000000000000001
-0000000400000000ffffffff000000740000008478666365342d73657373696f
-6e00000000000003000200040000000000010002000000000000000400000000
-000000c4000000ac000000b87866736d2d6c6f676f7574000000000100000004
+0002000400000000ffffffff000000740000008478666365342d73657373696f
+6e00000000000003000200040000000000010004000000000000000200000000
+000000c4000000ac000000b87866736d2d6c6f676f7574000000000100020004
 00000000ffffffff000000d0000000e073797374656d2d73757370656e640000
-000000010000000400000000ffffffff000000f8000001087866736d2d686962
-65726e6174650000000000010000000400000000000001440000012000000130
-73797374656d2d73687574646f776e0000000002000100020000000000000004
+000000010002000400000000ffffffff000000f8000001087866736d2d686962
+65726e6174650000000000010002000400000000000001440000012000000130
+73797374656d2d73687574646f776e0000000002000200040000000000000002
 00000000ffffffff00000150000001607866736d2d73757370656e6400000000
-00000001000000040000000000000194000001780000018878666365342d7370
-6c61736800000000000000010000000400000000ffffffff000001a0000001b0
-73797374656d2d6c6f672d6f75740000000000010000000400000000000001e4
-000001c8000001d873797374656d2d7265626f6f740000000000000100000004
+00000001000200040000000000000194000001780000018878666365342d7370
+6c61736800000000000000010002000400000000ffffffff000001a0000001b0
+73797374656d2d6c6f672d6f75740000000000010002000400000000000001e4
+000001c8000001d873797374656d2d7265626f6f740000000000000100020004
 0000000000000214000001f0000002007866736d2d73687574646f776e000000
-0000000200010002000000000000000400000000ffffffff000002200000022c
-7866736d2d7265626f6f74000000000100000004000000000000000300000248
-000002540000026434387834382f6170707300007363616c61626c652f617070
-73000000313238783132382f6170707300000000
+0000000200020004000000000000000200000000ffffffff000002200000022c
+7866736d2d7265626f6f74000000000100020004000000000000000300000248
+00000258000002687363616c61626c652f61707073000000313238783132382f
+617070730000000034387834382f617070730000
--8<---------------cut here---------------end--------------->8---

These files are created by ‘gtk-update-icon-cache’.

Most likely the same issue as with GDK: <https://bugs.gnu.org/25414>.

Ludo’.