Tools/osbuild-image-info: rework analyse_iso()

Rework the function to actually fail in case it can't analyze the
provided ISO. Previously, the tool would silently fail to analyze ISO,
generate and generate an empty report. Fix this.

Signed-off-by: Tomáš Hozza <thozza@redhat.com>

tools/osbuild-image-info

@@ -2919,15 +2919,8 @@ def is_iso(path):
 
 
 def analyse_iso(path):
-    with tempfile.TemporaryDirectory(dir="/var/tmp") as tmp:
-        report = None
-        subprocess.run(["mount", "-o", "loop", path, tmp], check=True)
-        try:
-            report = analyse_tarball(os.path.join(tmp, "liveimg.tar.gz"))
-        except Exception as e:
-            print(f"{e}", file=sys.stderr)
-        subprocess.run(["umount", tmp], check=True)
-        return report
+    with mount(path, ["loop"]) as tmp:
+        return analyse_tarball(os.path.join(tmp, "liveimg.tar.gz"))
 
 
 def main():