Allow passing abbrev to describe (#1084)

This provides ability for user to request full commit through API

dulwich/porcelain.py

@@ -1985,11 +1985,12 @@ def find_unique_abbrev(object_store, object_id):
     return object_id.decode("ascii")[:7]
 
 
-def describe(repo):
+def describe(repo, abbrev=7):
     """Describe the repository version.
 
     Args:
       repo: git repository
+      abbrev: number of characters of commit to take, default is 7
     Returns: a string description of the current git revision
 
     Examples: "gabcdefh", "v0.1" or "v0.1-5-gabcdefh".
@@ -2045,13 +2046,13 @@ def describe(repo):
                         return "{}-{}-g{}".format(
                             tag_name,
                             commit_count,
-                            latest_commit.id.decode("ascii")[:7],
+                            latest_commit.id.decode("ascii")[:abbrev],
                         )
 
             commit_count += 1
 
         # Return plain commit if no parent tag can be found
-        return "g{}".format(latest_commit.id.decode("ascii")[:7])
+        return "g{}".format(latest_commit.id.decode("ascii")[:abbrev])
 
 
 def get_object_by_path(repo, path, committish=None):

dulwich/tests/test_porcelain.py

@@ -2990,6 +2990,38 @@ class DescribeTests(PorcelainTestCase):
             porcelain.describe(self.repo.path),
         )
 
+    def test_tag_and_commit_full(self):
+        fullpath = os.path.join(self.repo.path, "foo")
+        with open(fullpath, "w") as f:
+            f.write("BAR")
+        porcelain.add(repo=self.repo.path, paths=[fullpath])
+        porcelain.commit(
+            self.repo.path,
+            message=b"Some message",
+            author=b"Joe <joe@example.com>",
+            committer=b"Bob <bob@example.com>",
+        )
+        porcelain.tag_create(
+            self.repo.path,
+            b"tryme",
+            b"foo <foo@bar.com>",
+            b"bar",
+            annotated=True,
+        )
+        with open(fullpath, "w") as f:
+            f.write("BAR2")
+        porcelain.add(repo=self.repo.path, paths=[fullpath])
+        sha = porcelain.commit(
+            self.repo.path,
+            message=b"Some message",
+            author=b"Joe <joe@example.com>",
+            committer=b"Bob <bob@example.com>",
+        )
+        self.assertEqual(
+            "tryme-1-g{}".format(sha.decode("ascii")),
+            porcelain.describe(self.repo.path, abbrev=40),
+        )
+
 
 class PathToTreeTests(PorcelainTestCase):
     def setUp(self):