fix #2588 breaking launch.py (. . .)

launch.py

@@ -9,7 +9,7 @@ import platform
 dir_repos = "repositories"
 python = sys.executable
 git = os.environ.get('GIT', "git")
-index_url = os.environ.get('INDEX_URL',"")
+index_url = os.environ.get('INDEX_URL', "")
 
 
 def extract_arg(args, name):
@@ -58,7 +58,8 @@ def run_python(code, desc=None, errdesc=None):
 
 
 def run_pip(args, desc=None):
-    return run(f'"{python}" -m pip {args} --prefer-binary{f' --index-url {index_url}' if index_url!='' else ''}', desc=f"Installing {desc}", errdesc=f"Couldn't install {desc}")
+    index_url_line = f' --index-url {index_url}' if index_url != '' else ''
+    return run(f'"{python}" -m pip {args} --prefer-binary{index_url_line}', desc=f"Installing {desc}", errdesc=f"Couldn't install {desc}")
 
 
 def check_run_python(code):