static: prepare for update to black 19.10b0 (#3183)

Signed-off-by: Sergio Schvezov <sergio.schvezov@canonical.com>

Author: Sergio Schvezov

snapcraft/plugins/v1/_ros/wstool.py

@@ -161,14 +161,15 @@ def _run(self, arguments: List[str]) -> str:
         if "LD_LIBRARY_PATH" in env:
             env["LD_LIBRARY_PATH"] += ":"
         ld_library_path = env.get("LD_LIBRARY_PATH", "")
-        env[
-            "LD_LIBRARY_PATH"
-        ] = ld_library_path + snapcraft.formatting_utils.combine_paths(
-            snapcraft.common.get_library_paths(
-                self._wstool_install_path, self._project.arch_triplet
-            ),
-            prepend="",
-            separator=":",
+        env["LD_LIBRARY_PATH"] = (
+            ld_library_path
+            + snapcraft.formatting_utils.combine_paths(
+                snapcraft.common.get_library_paths(
+                    self._wstool_install_path, self._project.arch_triplet
+                ),
+                prepend="",
+                separator=":",
+            )
         )
 
         # Make sure git can be used out of the wstool install path instead of needing