[git] Migrate git method from Ruby to Python (#178)

The main reason for doing this is to have some common code between scripts, so that it is easier to change the JSON schema globally and normalize a few things (such as release order).

The Ruby code was kept as is so we can quickly roll back if necessary.

src/git.py

@@ -0,0 +1,55 @@
+import regex as re
+import sys
+from common import endoflife
+from common.git import Git
+from liquid import Template
+
+"""Fetch versions with their dates from tags in a git repository.
+
+This replace the old update.rb script.
+
+Note that this script is using the regex module because the Python re module does not support
+identically named groups (as used in the mariadb product).
+"""
+
+# Default tag template and regex should include tiny version to properly handle blender,
+# craft-cms, exim, gerrit, jquery, kdeplasma, kirby, logstash, nexus, silverstripe
+# and tarantool versions.
+METHOD = 'git'
+DEFAULT_VERSION_REGEX = r"^v?(?P<major>[1-9]\d*)\.(?P<minor>\d+)(\.(?P<patch>\d+)(\.(?P<tiny>\d+))?)?$"
+DEFAULT_TAG_TEMPLATE = "{{major}}.{{minor}}{% if patch %}.{{patch}}{% if tiny %}.{{tiny}}{%endif%}{%endif%}"
+
+
+def fetch_releases(product_name, url, regex, template):
+    releases = {}
+
+    git = Git(url)
+    git.setup(bare=True)
+
+    tags = git.list_tags()
+    for tag, date in tags:
+        match = re.match(regex, tag)
+        if match:
+            version = Template(template).render(match.groupdict())
+            releases[version] = date
+            print(f"{version}: {date}")
+
+    return releases
+
+def update_product(product_name, configs):
+    releases = {}
+
+    for config in configs:
+        t = config.get("template", DEFAULT_TAG_TEMPLATE)
+        regex = config.get("regex", DEFAULT_VERSION_REGEX)
+        regex = regex.replace("(?<", "(?P<")  # convert ruby regex to python regex
+        releases = releases | fetch_releases(product_name, config[METHOD], regex, t)
+
+    endoflife.write_releases(product_name, releases)
+
+
+p_filter = sys.argv[1] if len(sys.argv) > 1 else None
+for product, configs in endoflife.list_products(METHOD, p_filter).items():
+    print(f"::group::{product}")
+    update_product(product, configs)
+    print("::endgroup::")