dokku: App start fails with error removing TMPDIR [Dokku 0.5.2]

Description of problem: After upgrading to Dokku version 0.5.2, I’m encountering the following problem which causes the container startup being rolled back. Essentially it seems that in cleanup(), rm is unable to remove the TMPDIR created.

Running dokku ps:restart <app>, everything seems fine until the final bit to cleanup.

=====> end <app> web container output
+ cleanup
+ declare 'desc=cleans up TMPDIR and print container output'
+ local id=
+ rm -rf /tmp/user/1000
rm: cannot remove ‘/tmp/user/1000’: Permission denied
+ kill_new bf7b0ffea6034f07a397131f31aebe415a0910e8662c117c4563df8a2e7f6962
+ declare 'desc=wrapper function to kill newly started app container'
+ local id=bf7b0ffea6034f07a397131f31aebe415a0910e8662c117c4563df8a2e7f6962
+ docker inspect bf7b0ffea6034f07a397131f31aebe415a0910e8662c117c4563df8a2e7f6962
+ docker stop bf7b0ffea6034f07a397131f31aebe415a0910e8662c117c4563df8a2e7f6962
+ docker kill bf7b0ffea6034f07a397131f31aebe415a0910e8662c117c4563df8a2e7f6962

I have tried rebuilding a fresh dokku instance from scratch and deploying my app, but the deployment fails with the same problem. The app runs fine on Dokku 0.4.14.

$ ll /tmp
drwx--x--x  3 root root 4096 Mar 29 08:21 user/

$ ll /tmp/user
drwx------ 2 dokku root 4096 Mar 29 08:34 1000/

$ uname -a
Linux App0 3.13.0-71-generic #114-Ubuntu SMP Tue Dec 1 02:34:22 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux

$ docker version
Client:
 Version:      1.10.3
 API version:  1.22
 Go version:   go1.5.3
 Git commit:   20f81dd
 Built:        Thu Mar 10 15:54:52 2016
 OS/Arch:      linux/amd64

Server:
 Version:      1.10.3
 API version:  1.22
 Go version:   go1.5.3
 Git commit:   20f81dd
 Built:        Thu Mar 10 15:54:52 2016
 OS/Arch:      linux/amd64

$ sigil -v
0.4.0