disk-image-create (2.27.2) fails to build RHEL7 ramdisk on Fedora

[Amit Goela]

There are several bugs:
1) If Python2 is not installed, it will error with unable to find env python. Manually creating a symlink /usr/bin/python -> /usr/bin/python3 resolves the issue.
2) When running disk-image-create, it will fail with the error "rhel is not supported" trying to install EPEL packages. Updating /usr/local/lib/python3.7/site-packages/diskimage_builder/elements/epel/pre-install.d/05-rpm-epel-release and /usr/local/lib/python3.7/site-packages/diskimage_builder/elements/epel/pkg-map to include "rhel" resolves the issue
3) If not setting FS_TYPE, disk-image-create returns an error find: './var/lib/yum/history/2019-09-24/9': Input/output error which causes the failure. It is using ext4 default FS, however, if running with FS_TYPE=xfs, this issue does not appear.
4) Error in 99-selinux-fixfiles-restore
2019-09-24 15:49:44.586 | dib-run-parts Running /tmp/dib_build.wOOv1tla/hooks/cleanup.d/99-selinux-fixfiles-restore
2019-09-24 15:50:21.399 | /tmp/dib_build.wOOv1tla/hooks/cleanup.d/99-selinux-fixfiles-restore: line 69: [: too many arguments