Allow guid to be empty when parsing or generating diaspora ID

Sometimes we just want a URI format Diaspora ID but don't have
a guid.

federation/tests/utils/test_diaspora.py

@@ -44,6 +44,7 @@ def test_get_fetch_content_endpoint():
 
 def test_parse_diaspora_uri():
     assert parse_diaspora_uri("diaspora://user@example.com/spam/eggs") == ("user@example.com", "spam", "eggs")
+    assert parse_diaspora_uri("diaspora://user@example.com/spam/") == ("user@example.com", "spam", "")
     assert parse_diaspora_uri("diaspora://user@example.com/spam/eggs@spam") == ("user@example.com", "spam", "eggs@spam")
     assert not parse_diaspora_uri("https://user@example.com/spam/eggs")
     assert not parse_diaspora_uri("spam and eggs")
@@ -57,6 +58,7 @@ def test_parse_profile_diaspora_id():
 
 def test_generate_diaspora_profile_id():
     assert generate_diaspora_profile_id("foobar@example.com", "1234") == "diaspora://foobar@example.com/profile/1234"
+    assert generate_diaspora_profile_id("foobar@example.com") == "diaspora://foobar@example.com/profile/"
 
 
 class TestRetrieveDiasporaHCard:

federation/utils/diaspora.py

@@ -163,11 +163,14 @@ def parse_profile_diaspora_id(id):
     return handle, guid
 
 
-def generate_diaspora_profile_id(handle, guid):
+def generate_diaspora_profile_id(handle, guid=None):
     """
     Generate a Diaspora profile ID from handle and guid.
+
+    Sometimes we don't know the guid if we just have a handle, but still we want to store it
+    in URI format.
     """
-    return "diaspora://%s/profile/%s" % (handle, guid)
+    return "diaspora://%s/profile/%s" % (handle, guid or "")
 
 
 def parse_profile_from_hcard(hcard, handle):