Fix test failure of test_XXX caused by upgrade of gpgme from 1.6.0 to
1.8.0:

======================================================================
FAIL: test_encrypt_to_signonly (tests.test_encrypt_decrypt.EncryptDecryptTestCase)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/tmp/guix-build-python2-pygpgme-0.3.drv-0/pygpgme-0.3/tests/test_encrypt_decrypt.py", line 185, in test_encrypt_to_signonly
    self.assertEqual(exc.args[0], gpgme.ERR_SOURCE_UNKNOWN)
AssertionError: 7 != 0

----------------------------------------------------------------------

Patch copied from the Debian package pygpgme-0.3-1.2:

https://sources.debian.net/src/pygpgme/0.3-1.2/debian/patches/0005-Fix-test-failures-with-pinentry.patch/

From: "Dr. Tobias Quathamer" <toddy@debian.org>
Date: Thu, 24 Nov 2016 12:20:54 +0100
Subject: Fix test failures with pinentry

---
 tests/test_encrypt_decrypt.py | 5 +++--
 tests/test_passphrase.py      | 2 ++
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/tests/test_encrypt_decrypt.py b/tests/test_encrypt_decrypt.py
index 21ae83e..05707e1 100644
--- a/tests/test_encrypt_decrypt.py
+++ b/tests/test_encrypt_decrypt.py
@@ -132,6 +132,7 @@ class EncryptDecryptTestCase(GpgHomeTestCase):
             os.write(fd, b'Symmetric passphrase\n')
         ctx = gpgme.Context()
         ctx.armor = True
+        ctx.pinentry_mode = gpgme.PINENTRY_MODE_LOOPBACK
         ctx.passphrase_cb = passphrase
         ctx.encrypt(None, 0, plaintext, ciphertext)
         self.assertTrue(
@@ -182,8 +183,8 @@ class EncryptDecryptTestCase(GpgHomeTestCase):
             ctx.encrypt([recipient], gpgme.ENCRYPT_ALWAYS_TRUST,
                         plaintext, ciphertext)
         except gpgme.GpgmeError as exc:
-            self.assertEqual(exc.args[0], gpgme.ERR_SOURCE_UNKNOWN)
-            self.assertEqual(exc.args[1], gpgme.ERR_GENERAL)
+            self.assertEqual(exc.args[0], gpgme.ERR_SOURCE_GPGME)
+            self.assertEqual(exc.args[1], gpgme.ERR_UNUSABLE_PUBKEY)
         else:
             self.fail('gpgme.GpgmeError not raised')
 
diff --git a/tests/test_passphrase.py b/tests/test_passphrase.py
index 35b3c59..05e6811 100644
--- a/tests/test_passphrase.py
+++ b/tests/test_passphrase.py
@@ -34,6 +34,7 @@ class PassphraseTestCase(GpgHomeTestCase):
         ctx = gpgme.Context()
         key = ctx.get_key('EFB052B4230BBBC51914BCBB54DCBBC8DBFB9EB3')
         ctx.signers = [key]
+        ctx.pinentry_mode = gpgme.PINENTRY_MODE_LOOPBACK
         plaintext = BytesIO(b'Hello World\n')
         signature = BytesIO()
 
@@ -55,6 +56,7 @@ class PassphraseTestCase(GpgHomeTestCase):
         ctx = gpgme.Context()
         key = ctx.get_key('EFB052B4230BBBC51914BCBB54DCBBC8DBFB9EB3')
         ctx.signers = [key]
+        ctx.pinentry_mode = gpgme.PINENTRY_MODE_LOOPBACK
         ctx.passphrase_cb = self.passphrase_cb
         plaintext = BytesIO(b'Hello World\n')
         signature = BytesIO()
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<tr><td><span title='2019-02-17 08:29:18 +0200'>2019-02-17</span></td><td><a href='/guix/commit/gnu/packages/irc.scm?id=3aeac37e61e44f63dd3fd29eb8f19b3b4993614c'>gnu: quassel: Update to 0.13.1.</a><span class='msg-avail'>...</span></td><td>Efraim Flashner</td></tr>
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<tr><td><span title='2019-01-10 16:05:42 -0500'>2019-01-10</span></td><td><a href='/guix/commit/gnu/packages/irc.scm?id=c954fe6622660f1511ced2be955c35acfb8b124a'>gnu: irssi: Update to 1.1.2 [fixes CVE-2019-5882].</a><span class='msg-avail'>...</span></td><td>Kei Kebreau</td></tr>
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<tr><td><span title='2018-12-08 22:50:17 +0200'>2018-12-08</span></td><td><a href='/guix/commit/gnu/packages/irc.scm?id=4ad62876cb85ebab8e8607afb5e90844acbcfafd'>gnu: quassel: Update to 0.13.0.</a><span class='msg-avail'>...</span></td><td>Efraim Flashner</td></tr>