while trying to buld a custom kali-live-build-config using the steps from:
http://docs.kali.org/development/live-build-a-custom-kali-iso
It reproduced an error described in the issue:
N: 0000270
link: https://bugs.kali.org/view.php?id=270
After following the recomended fix the process runs util the following error:
umount: /media/build-live/kali/live-build-config/chroot/proc: target is busy
(In some cases useful info about processes that
use the device is found by lsof(8) or fuser(1).)
P: Begin unmounting filesystems...
P: Saving caches...
Reading package lists...
Building dependency tree...
Reading state information...
Build of sana/default/amd64 live image failed (see build.log for details)

Build used the Vmware Vm provided by Kali-Linux 2.0 x64 (prebuild).
tryed before and after update's with the same result.

cat /etc/debian_version

Kali Linux 2.0

uname -a
Linux vm-neb01 4.0.0-kali1-amd64 0000001 SMP Debian 4.0.4-1+kali2 (2015-06-03) x86_64 GNU/Linux

Build log in attach.
PS:
since the vm default hd didn't had space for the build i creaded an aditional virtual hd with 20G where the build is currelty been executed from

mount after failed build:

mount
sysfs on /sys type sysfs (rw,nosuid,nodev,noexec,relatime)
proc on /proc type proc (rw,nosuid,nodev,noexec,relatime)
udev on /dev type devtmpfs (rw,relatime,size=10240k,nr_inodes=450851,mode=755)
devpts on /dev/pts type devpts (rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000)
tmpfs on /run type tmpfs (rw,nosuid,relatime,size=725588k,mode=755)
/dev/sda1 on / type ext4 (rw,relatime,errors=remount-ro,data=ordered)
securityfs on /sys/kernel/security type securityfs (rw,nosuid,nodev,noexec,relatime)
tmpfs on /dev/shm type tmpfs (rw,nosuid,nodev)
tmpfs on /run/lock type tmpfs (rw,nosuid,nodev,noexec,relatime,size=5120k)
tmpfs on /sys/fs/cgroup type tmpfs (ro,nosuid,nodev,noexec,mode=755)
cgroup on /sys/fs/cgroup/systemd type cgroup (rw,nosuid,nodev,noexec,relatime,xattr,release_agent=/lib/systemd/systemd-cgroups-agent,name=systemd)
pstore on /sys/fs/pstore type pstore (rw,nosuid,nodev,noexec,relatime)
cgroup on /sys/fs/cgroup/cpuset type cgroup (rw,nosuid,nodev,noexec,relatime,cpuset)
cgroup on /sys/fs/cgroup/cpu,cpuacct type cgroup (rw,nosuid,nodev,noexec,relatime,cpu,cpuacct)
cgroup on /sys/fs/cgroup/blkio type cgroup (rw,nosuid,nodev,noexec,relatime,blkio)
cgroup on /sys/fs/cgroup/devices type cgroup (rw,nosuid,nodev,noexec,relatime,devices)
cgroup on /sys/fs/cgroup/freezer type cgroup (rw,nosuid,nodev,noexec,relatime,freezer)
cgroup on /sys/fs/cgroup/net_cls,net_prio type cgroup (rw,nosuid,nodev,noexec,relatime,net_cls,net_prio)
cgroup on /sys/fs/cgroup/perf_event type cgroup (rw,nosuid,nodev,noexec,relatime,perf_event)
tmpfs on /etc/machine-id type tmpfs (ro,relatime,size=725588k,mode=755)
systemd-1 on /proc/sys/fs/binfmt_misc type autofs (rw,relatime,fd=23,pgrp=1,timeout=300,minproto=5,maxproto=5,direct)
mqueue on /dev/mqueue type mqueue (rw,relatime)
hugetlbfs on /dev/hugepages type hugetlbfs (rw,relatime)
debugfs on /sys/kernel/debug type debugfs (rw,relatime)
fusectl on /sys/fs/fuse/connections type fusectl (rw,relatime)
vmware-vmblock on /run/vmblock-fuse type fuse.vmware-vmblock (rw,nosuid,nodev,relatime,user_id=0,group_id=0,default_permissions,allow_other)
binfmt_misc on /proc/sys/fs/binfmt_misc type binfmt_misc (rw,relatime)
tmpfs on /run/user/133 type tmpfs (rw,nosuid,nodev,relatime,size=362796k,mode=700,uid=133,gid=144)
tmpfs on /run/user/0 type tmpfs (rw,nosuid,nodev,relatime,size=362796k,mode=700)
/dev/sdb1 on /media/build-live type ext4 (rw,relatime,data=ordered)
proc-live on /media/build-live/kali/live-build-config/chroot/proc type proc (rw,relatime)
gvfsd-fuse on /run/user/0/gvfs type fuse.gvfsd-fuse (rw,nosuid,nodev,relatime,user_id=0,group_id=0)