[FIX] forwardport: don't keep the commit date

This is not super useful and causes issues with runbot as it uses
commit dates to decide how "old" branches are, and ignores (doesn't
create when it scans them) branches more than a month old.

So the forwardport branches will be completely ignored (not considered
let alone tested) if we happen to forward-port a PR last updated more
than a month ago. Which is somewhat inconvenient.

Closes #274

forwardport/models/project.py

@@ -702,6 +702,7 @@ More info at https://github.com/odoo/odoo/wiki/Mergebot#forward-port
             conf = working_copy.with_config(env={
                 **to_dict('AUTHOR', author),
                 **to_dict('COMMITTER', committer),
+                'GIT_COMMITTER_DATE': '',
             })
             # squash to a single commit
             conf.reset('--soft', root_commits[0]['parents'][0]['sha'])
@@ -759,7 +760,6 @@ stderr:
                 'GIT_AUTHOR_DATE': cm['author']['date'],
                 'GIT_COMMITTER_NAME': cm['committer']['name'],
                 'GIT_COMMITTER_EMAIL': cm['committer']['email'],
-                'GIT_COMMITTER_DATE': cm['committer']['date'],
             })
 
             conf = configured.with_config(stdout=subprocess.PIPE, stderr=subprocess.PIPE, check=False)

forwardport/tests/test_simple.py

@@ -389,7 +389,9 @@ def test_conflict(env, config, make_repo):
     p = prod.commit(p_0)
     c = prod.commit(pr1.head)
     assert c.author == p.author
-    assert c.committer == p.committer
+    # ignore date as we're specifically not keeping the original's
+    without_date = itemgetter('name', 'email')
+    assert without_date(c.committer) == without_date(p.committer)
     assert prod.read_tree(c) == {
         'f': 'c',
         'g': re_matches(r'''<<<\x3c<<< HEAD