PIN entry fails after setup

[romanz]

$ killall trezor-gpg-agent
$ trezor-gpg init "Roman Zeyde <roman.zeyde@gmail.com>" -v
Use the numeric keypad to describe number positions. The layout is:
    7 8 9
    4 5 6
    1 2 3
Please enter current PIN: 

2017-11-10 22:19:23,582 INFO         creating new nist256p1 GPG primary key for "Roman Zeyde <roman.zeyde@gmail.com>"                     [__init__.py:62]
2017-11-10 22:19:23,582 INFO         please confirm GPG signature on Trezor for "<gpg://Roman Zeyde <roman.zeyde@gmail.com>|nist256p1>"... [client.py:35]
2017-11-10 22:19:25,813 INFO         please confirm GPG signature on Trezor for "<gpg://Roman Zeyde <roman.zeyde@gmail.com>|nist256p1>"... [client.py:35]
gpg: inserting ownertrust of 6
gpg: checking the trustdb
gpg: marginals needed: 3  completes needed: 1  trust model: PGP
gpg: depth: 0  valid:   1  signed:   0  trust: 0-, 0q, 0n, 0m, 0f, 1u
/home/roman/.gnupg/trezor/pubring.kbx
-------------------------------------
sec   nistp256/0A133CA3 2017-11-10 [SC]
uid         [ultimate] Roman Zeyde <roman.zeyde@gmail.com>
ssb   nistp256/276C82DC 2017-11-10 [E]

$ trezorctl clear_session
Session cleared
$ echo 123 | gpg2 --sign -a
gpg: using "Roman Zeyde <roman.zeyde@gmail.com>" as default secret key for signing
gpg: signing failed: End of file
-----BEGIN PGP MESSAGE-----
Version: GnuPG v2

gpg: signing failed: End of file
$ killall trezor-gpg-agent
$ echo 123 | gpg2 --sign -a
gpg: using "Roman Zeyde <roman.zeyde@gmail.com>" as default secret key for signing
-----BEGIN PGP MESSAGE-----
Version: GnuPG v2

owGbwMvMwCV8zX3aRC5hm8WMpzmTGKLYOH8ZGnF1xLEwCHMxsLEygQQYuDgFYKqU
yhj+Gfs8E9II3ZYXq7Nxl2d4fVK53TN5EQYRaQ3F2Wdnnz/ykuGf5t+2YF99E4UY
MfG9Qp2egbJfyg0lpWyux5abLNRrU2YBAA==
=c19V
-----END PGP MESSAGE-----
$ 

gpg-agent.log contains:

2017-11-10 22:19:37,811 ERROR        PIN entry failed: b'Traceback (most recent call last):\n  File "<string>", line 1, in <module>\n  File "/home/roman/.local/lib/python3.5/site-packages/pymsgbox/__init__.py", line 118, in password\n    return __fillablebox(text, title, default, mask=mask, root=root, timeout=timeout)\n  File "/home/roman/.local/lib/python3.5/site-packages/pymsgbox/__init__.py", line 282, in __fillablebox\n    boxRoot = tk.Tk()\n  File "/usr/lib/python3.5/tkinter/__init__.py", line 1871, in __init__\n    self.tk = _tkinter.create(screenName, baseName, className, interactive, wantobjects, useTk, sync, use)\n_tkinter.TclError: no display name and no $DISPLAY environment variable\n' [trezor.py:33]
2017-11-10 22:19:37,811 ERROR        ping failed: Command '['/usr/bin/python3', '-c', 'import sys, pymsgbox; sys.stdout.write(pymsgbox.password(sys.stdin.read()))']' returned non-zero exit status 1 [trezor.py:92]