pq: Parse DEP3 headers

Currently the patch headers in DEP3 format are partially
supported, as git's mailinfo only reads the From and Subject fields from
the first paragraph. But the default in dep3 patches is Description and
Author, that are ignored by git. Even worse, when this fields are in the
first paragraph (again the default) git mailinfo drops all the contained
information.

This patch parses the dep3 headers if git's mailinfo couldn't obtain any
useful information, any header other than Subject|Description and
Author|From is appended to the patch message.

The description field is splitted in first line for the short
description and the rest is prepended to the patch message.

Closes: #785274

1 files changed, 19 insertions, 0 deletions

diff --git a/tests/component/__init__.py b/tests/component/__init__.py
index 84acf6a6..c670851f 100644
--- a/tests/component/__init__.py
+++ b/tests/component/__init__.py
@@ -86,6 +86,25 @@ class ComponentTestGitRepository(GitRepository):
         blobs = [obj[3] for obj in objs if obj[1] == 'blob']
         return set(blobs)
 
+    def get_head_author_subject(self):
+        out, err, ret = self._git_inout('format-patch', ['-1', '--stdout', '--subject-prefix='],
+                                        capture_stderr=True)
+        if ret:
+            raise GitRepositoryError("Cannot get head author/subject: %s" %
+                                     err.strip())
+
+        output = out.decode('utf-8')
+        for line in output.split('\n'):
+            line = line.strip()
+            if not line:
+                # end of headers
+                break
+            if line.startswith('From:'):
+                author = line.replace('From:', '').strip()
+            elif line.startswith('Subject:'):
+                subject = line.replace('Subject:', '').strip()
+        return author, subject
+
 
 class ComponentTestBase(unittest.TestCase, GbpLogTester):
     """Base class for testing cmdline tools of git-buildpackage"""