temporal modules: Fixed usage of the 'z' flag; inform user then -z flag is switched on (much slower) (trunk, https://trac.osgeo.org/grass/changeset/66319 + https://trac.osgeo.org/grass/changeset/66341)

git-svn-id: https://svn.osgeo.org/grass/grass/branches/releasebranch_7_0@66342 15284696-431f-4ddb-bdfa-cd5b030d7da7

temporal/t.rast.series/t.rast.series.py

@@ -99,7 +99,10 @@ def main():
 
         file.close()
 
-        flag = "z"
+        flag = ""
+        if len(rows) > 1000:
+            grass.warning(_("Processing over 1000 maps: activating -z flag of r.series which slows down processing"))
+            flag += "z"
         if nulls:
             flag += "n"