Add a --distro option to build-deb.py

Add an optional --distro argument to build-deb.py, to specify the Debian
version in the package name, which currently is "1". This option may
prove useful when publishing packages to freedomofpress/apt-tools-prod,
where packages from different distros with the same names but different
contents are not accepted.

install/linux/build-deb.py

@@ -1,5 +1,7 @@
 #!/usr/bin/env python3
 # -*- coding: utf-8 -*-
+
+import argparse
 import inspect
 import os
 import shutil
@@ -21,6 +23,22 @@ def run(cmd):
 
 
 def main():
+    parser = argparse.ArgumentParser(
+        prog=sys.argv[0],
+        description="Dev script for building Dangerzone debs",
+    )
+    # FIXME: The name of the distro is important, as it can help users who are upgrading
+    # from a distro version to another. If we *do* need to provide a name at some point,
+    # here's a suggestion on how we should tackle naming:
+    #
+    # https://github.com/freedomofpress/dangerzone/pull/322#issuecomment-1428665162
+    parser.add_argument(
+        "--distro",
+        required=False,
+        help="The name of the Debian-based distro",
+    )
+    args = parser.parse_args()
+
     dist_path = os.path.join(root, "dist")
     deb_dist_path = os.path.join(root, "deb_dist")
 
@@ -31,13 +49,31 @@ def main():
         shutil.rmtree(deb_dist_path)
 
     print("* Building DEB package")
-    # This command also builds the Debian source package, and then creates the DEB
-    # package, meaning that we don't need to run `sdist_dsc` as well.
-    run(["python3", "setup.py", "--command-packages=stdeb.command", "bdist_deb"])
+    # NOTE: This command first builds the Debian source package, and then creates the
+    # final DEB package. We could simply call `bdist_deb`, which performs `sdist_dsc`
+    # implicitly, but we wouldn't be able to pass the Debian version argument. Because
+    # we do this in a single invocation though, there's no performance cost.
+    if args.distro is None:
+        deb_ver_args = ()
+        deb_ver = "1"
+    else:
+        deb_ver_args = ("--debian-version", args.distro)
+        deb_ver = args.distro
+
+    run(
+        [
+            "python3",
+            "setup.py",
+            "--command-packages=stdeb.command",
+            "sdist_dsc",
+            *deb_ver_args,
+            "bdist_deb",
+        ]
+    )
 
     print("")
     print("* To install run:")
-    print("sudo dpkg -i deb_dist/dangerzone_{}-1_all.deb".format(version))
+    print(f"sudo dpkg -i deb_dist/dangerzone_{version}-{deb_ver}_all.deb")
 
 
 if __name__ == "__main__":