Note:

The 'sysfiles' package is registering mime types in /etc/mime.types which
is provided by the 'mime-support' package. Because the 'sysfiles' package
is build at stage 1 whereas the 'mime-support' package only when it's
explicitely requested by only cross-compiling the target we will end up
with shared files ("/etc/mime.types") between both packages when building
a target "natively", because "/etc/mime.types" was already created while
building 'sysfiles'.
To circumvent this issue we always need to build the 'mime-support' package
at stage 1.