Speeding up firedrake-install through shallow git clone

[weshouman]

The install script could be sped up considerably if the git clone depth got set to 1, what do you think of that?

--- firedrake-install-origin	2022-10-23 00:20:01.729146902 +0000
+++ firedrake-install	2022-10-23 00:18:07.922518821 +0000
@@ -812,13 +812,13 @@
         if options["disable_ssh"]:
             raise InstallError("Skipping ssh clone because --disable-ssh")
         # note: so far only loopy requires submodule
-        check_call(["git", "clone", "-q", "--recursive", git_url(plain_url, "ssh")])
+        check_call(["git", "clone", "-q", "--recursive", "--depth 1", git_url(plain_url, "ssh")])
         log.info("Successfully cloned repository %s" % name)
     except (subprocess.CalledProcessError, InstallError):
         if not options["disable_ssh"]:
             log.warning("Failed to clone %s using ssh, falling back to https." % name)
         try:
-            check_call(["git", "clone", "-q", "--recursive", git_url(plain_url, "https")])
+            check_call(["git", "clone", "-q", "--recursive", "--depth", "1", git_url(plain_url, "https")])
             log.info("Successfully cloned repository %s." % name)
         except subprocess.CalledProcessError:
             log.error("Failed to clone %s branch %s." % (name, branch))

[dham]

The install script spends seconds cloning git repositories and then tens of minutes building PETSc. Using shallow clones isn't going to materially change the install time but it will make life difficult for anyone wishing to develop any part of Firedrake. I don't really see the win here.