read-version: fallback to get_version when git describe fails (#4366)

Annotated git tags are not present in shallow git clones. In shallow
clones, git describe may fail with exit 128 with one of the following
errors:
 - No tags can describe <hash>
 - No names found, cannot describe anything

If either message is present, fallback to
cloudinit.version.version_string.

This fixes readthedocs CI builds which may use git clone --depth 1 in
Annotated git tags are not present in shallow git clones. In shallow
clones, git describe may fail with exit 128 with one of the following
errors:
 - No tags can describe <hash>
 - No names found, cannot describe anything

If either message is present, fallback to
cloudinit.version.version_string.

Also pin sphinx=7.1.2 as the release 7.2.0 on  August 17 dropped the
extension setup_js_tag_helper used by our sphinx builds.

This fixes readthedocs CI builds which may use git clone --depth 1 in
the doc build process.

doc-requirements.txt

@@ -2,7 +2,7 @@ doc8
 furo
 m2r2
 pyyaml
-sphinx
+sphinx==7.1.2
 sphinx-design
 sphinx-copybutton
 sphinx-notfound-page

tools/read-version

@@ -89,7 +89,12 @@ def get_version_from_git(
                 version = tiny_p(cmd).strip()
                 version_long = tiny_p(cmd + ["--long"]).strip()
             except subprocess.CalledProcessError as e:
-                if "No tags can describe" not in e.stderr:
+                if not any(
+                    [
+                        "No tags can describe" in e.stderr,
+                        "cannot describe anything" in e.stderr,
+                    ]
+                ):
                     raise
                 version = src_version
                 version_long = ""