Bug#849168: pbuilder: Expect programe reported "no more ptys" and failed in rebuilding gcc with normal (non-root) user

[Xiangyu LIU]

Package: pbuilder
Version: 0.227
Severity: minor

Dear Pbuilder Maintainers,

   I want to rebuild locally gcc-5 and gcc-4.9 in current stretch by pbuilder.

   
   I download the source of gcc-5 (Debian) and gcc-4.9 (from Ubuntu) and rebuild by "sudo pbuilder build gcc-xxxxx.dsc".
   But building failed with reporting:
      "The system has no more ptys. Ask your system administrator to create more."
      "while executing"
      "spawn ls"

   I gave a try in Pbuilder with root user:
   # expect -c "spawn ls"
   It is OK to output "spawn ls"

   But when I type above command with normal user:
   rleigh at WFA256:/$ expect -c "spawn ls"
                     spawn ls
                    The system has no more ptys.  Ask your system administrator to create more.
                    while executing
                    "spawn ls"
   rleigh at WFA256:/$

   I check the /dev/pts, it was mounted in Pbuilder (with both root/normal users):
       rleigh at WFA256:/$ mount | grep pts
                        none on /dev/pts type devpts (rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000)

       root at WFA256:/# mount | grep pts
                        none on /dev/pts type devpts (rw,nosuid,noexec,relatime,gid=5,mode=620,ptmxmode=000)
  

   I have same issue in sbuild if I rebuild gcc by:
      $ sbuild -d stretch gcc-xxxx.dsc

   But it is OK if rebuild with root user:
      $ sudo sbuild -d stretch gcc-xxxx.dsc


   Yes I can rebuild gcc by sudo sbuild, but I don't know what is happening in Pbuilder or Sbuild with normal user.
   Any comment or advice would be very appreciated !


   Thanks,
   Best Regards,
   Xiangyu LIU


-- System Information:
Debian Release: stretch/sid
  APT prefers testing
  APT policy: (500, 'testing')
Architecture: amd64 (x86_64)

Kernel: Linux 4.8.15-02.custom.slackware-sign (SMP w/4 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/bash
Init: systemd (via /run/systemd/system)

Versions of packages pbuilder depends on:
ii  debconf [debconf-2.0]  1.5.59
ii  debootstrap            1.0.87
ii  dpkg-dev               1.18.15
ii  wget                   1.18-4

Versions of packages pbuilder recommends:
ii  devscripts  2.16.10
ii  eatmydata   105-5
pn  fakeroot    <none>
ii  iproute2    4.8.0-1
ii  net-tools   1.60+git20150829.73cef8a-2.2
ii  sudo        1.8.17p1-2

Versions of packages pbuilder suggests:
pn  cowdancer   <none>
pn  gdebi-core  <none>

-- debconf information:
  pbuilder/rewrite: false
  pbuilder/nomirror:
  pbuilder/mirrorsite: http://ftp.jaist.ac.jp/pub/Linux/debian/