switch_to_new_mapset changes to enable using existing mapset

src/grass_gis_helpers/mapset.py

@@ -22,12 +22,14 @@
 import grass.script as grass
 
 
-def switch_to_new_mapset(new_mapset):
+def switch_to_new_mapset(new_mapset, new = True):
     """The function switches to a new mapset and changes the GISRC file for
     parallel processing.
 
     Args:
         new_mapset (string): Unique name of the new mapset
+        new (boolean): Boolean if existing mapset should be used 
+                       or a new one created
     Returns:
         gisrc (string): The path of the old GISRC file
         newgisrc (string): The path of the new GISRC file
@@ -39,8 +41,12 @@ def switch_to_new_mapset(new_mapset):
     location = env["LOCATION_NAME"]
     old_mapset = env["MAPSET"]
 
-    grass.message(_(f"New mapset {new_mapset}"))
-    grass.utils.try_rmdir(os.path.join(gisdbase, location, new_mapset))
+    if new:
+        grass.message(_(f"New mapset {new_mapset}"))
+        grass.utils.try_rmdir(os.path.join(gisdbase, location, new_mapset))
+    else:
+        grass.message(_(f"Using, not deleting mapset {new_mapset}"))
+        grass.try_remove(os.path.join(gisdbase, location, new_mapset, ".gislock"))
 
     gisrc = os.environ["GISRC"]
     newgisrc = f"{gisrc}_{os.getpid()}"