Don't report a broken watch file when uscan reports the package is up to date.

When uscan reports a package is up to date, its return code is 1,
which is interpreted as an issue with uscan/watch by the dashboard.
So, before returning an issue for this package, check if the
output of uscan contains "Package is up to date".

Signed-off-by: Dylan Aïssi <dylan.aissi@collabora.com>

bin/packaging-updates

@@ -154,15 +154,23 @@ def compute_updates(data):
                     logging.warning(
                         f"{package.name}: uscan issue: {p.stderr.strip().decode()}"
                     )
+                p_stdout = p.stdout.strip().decode()
                 if p.returncode != 0:
-                    warning(
-                        package.name,
-                        Report.UPDATE_USCAN_WATCH_ISSUE,
-                        branch=package.git["default_branch"],
+                    is_up_to_date = re.findall(
+                        r".*Package is up to date from.*", p_stdout
                     )
+                    if is_up_to_date:
+                        logging.info(
+                            f"Package {package.name} is up-to-date according to its debian/watch file"
+                        )
+                    else:
+                        warning(
+                            package.name,
+                            Report.UPDATE_USCAN_WATCH_ISSUE,
+                            branch=package.git["default_branch"],
+                        )
                     return newver, newurl
 
-                p_stdout = p.stdout.strip().decode()
                 newver = re.findall(r"\$newversion .*", p_stdout)[0]
                 newver = newver.split()[-1]
                 newurl = re.findall(r"Upstream URL.*", p_stdout)[0]