Bug#621706: It was a system bug after all
reassign 621706 xkb-data
retitle 621706 il (Israel) variant si1452 mistakenly mapped to ie (Ireland)
I played with it more, and found the real problem: xkb-data includes the file
/usr/share/X11/xkb/rules/base, which maps il(si1452) to ie(basic) in several
locations and variations. This is caused by what seems to be a typo in the
package source: The file rules/compat/variantsMapping.lst, line 16, says:
il si1452 ie basic
This is completely wrong. Mapping to "il basic" may have been correct a long
time ago, but it isn't correct anymore; the line should simply be removed.
I am not sure, and don't know exactly where to look, but I suspect the bug is
in upstream (similar behavior has been reported by an Arch user).
Of course, the simplest workaround for me (since this is a variant I was
adding anyway) is to use a different name.