cli: Prevent . from being added to CLOE_PLUGIN_PATH

An empty entry in LD_LIBRARY_PATH is interpreted as the current
working directory. Conan sets LD_LIBRARY_PATH in such a way that
it inserts an empty entry, inadvertently.

Author: cassava

cli/cloe_launch/exec.py

@@ -429,6 +429,12 @@ def _extract_plugin_paths(self, env: Environment) -> List[Path]:
         """Return all Cloe plugin paths we find in LD_LIBRARY_PATH."""
         plugin_paths = []
         for libdir in env.get_list("LD_LIBRARY_PATH", default=[]):
+            # Conan defines LD_LIBRARY_PATH like this:
+            #   LD_LIBRARY_PATH=...:$LD_LIBRARY_PATH
+            # If the initial value is empty, this leads to an empty item in the list;
+            # we don't want this to be interpreted as CWD.
+            if len(libdir) == 0:
+                continue
             pp = Path(libdir) / "cloe"
             if pp.exists():
                 plugin_paths.append(pp)