hgk: no committer please

Generate committer only if we really have it.
Update test-hgk.t accordingly.

hgext/hgk.py

@@ -108,9 +108,10 b' def catcommit(ui, repo, n, prefix, ctx=N'
     if lines and lines[-1].startswith('committer:'):
         committer = lines[-1].split(': ')[1].rstrip()
     else:
-        committer = ctx.user()
+        committer = ""
 
     ui.write(("author %s %s %s\n" % (ctx.user(), int(date[0]), date[1])))
+    if committer != '':
     ui.write(("committer %s %s %s\n" % (committer, int(date[0]), date[1])))
     ui.write(("revision %d\n" % ctx.rev()))
     ui.write(("branch %s\n\n" % ctx.branch()))

tests/test-hgk.t

@@ -11,7 +11,6 b' Minimal hgk check'
   tree a0c8bcbbb45c
   parent 000000000000
   author test 0 0
-  committer test 0 0
   revision 0
   branch default