Just get all branches pushed to all remote repos with me as the committer.

my_git_branches.py

import datetime
from github import Github

g = Github('token')
me = g.get_user()
repos = me.get_repos()

def is_a_repo_contributor(repo):
    contributors = repo.get_contributors()
    return me.id in map(lambda con: con.id, contributors)

repos_with_me = filter(is_a_repo_contributor, repos)

def is_my_branch(branch):
    try:
        return me.id == branch.commit.committer.id
    except:
        return False

class RepoBranches:
    def __init__(self, repo, branches):
        self.repo = repo
        self.branches = branches

my_repo_branch_mappings = []
for repo in repos_with_me:
    branches = repo.get_branches()
    my_branches = filter(is_my_branch, branches)

    my_repo_branch_mappings.append(RepoBranches(repo, my_branches))

class BranchDate:
    def __init__(self, branch, last_modified):
        self.branch = branch
        self.last_modified = last_modified

branch_date_mappings = []
for repo_branch_mapping in my_repo_branch_mappings:
    for branch in repo_branch_mapping.branches:
        branch_last_modified = datetime.datetime.strptime(branch.commit.last_modified, '%a, %d %b %Y %H:%M:%S %Z')
        branch_date_mappings.append(BranchDate(branch, branch_last_modified))

sorted_branch_date_mappings = sorted(branch_date_mappings, key=lambda x: x.last_modified)
for item in sorted_branch_date_mappings[-10:]:
    print(item)