Fixed bug with empty LD_LIBRARY_PATH environment variable

Signed-off-by: Nicola Vigano <nicola.vigano@esrf.fr>

dct_launch.py

@@ -66,8 +66,12 @@ class DCTLauncher(object):
             self.conf = dct.dct_io_xml.DCTConf(self.confPath)
 
             # Adding runtime libraries
+            try:
+                env_initial = os.environ["LD_LIBRARY_PATH"]
+            except KeyError:
+                env_initial = ""
+
             libs = self.conf.getRuntimeLibraries()
-            env_initial = os.environ["LD_LIBRARY_PATH"]
             for lib in libs:
                 env_var = os.environ["LD_LIBRARY_PATH"]
                 os.environ["LD_LIBRARY_PATH"] = ":".join([env_var, lib])