[PATCH] Avoid using Mercurial extension

[Wald Commits]

# HG changeset patch
# User Tom Gottfried <tom at intevation.de>
# Date 1591275182 -7200
#      Thu Jun 04 14:53:02 2020 +0200
# Branch 3.2.x
# Node ID 21c89e39ca7243e0d7d5aac423969af6dd563b20
# Parent  e5d1a10d54aedc16985b43ef6bffd6cbdc1953bd
Avoid using Mercurial extension

purge is not activated by default and using a fresh temp directory
with new repo clones is now the default, anyhow.

diff -r e5d1a10d54ae -r 21c89e39ca72 contrib/make_flys_release/make_release.sh
--- a/contrib/make_flys_release/make_release.sh	Wed Jun 03 08:54:48 2020 +0200
+++ b/contrib/make_flys_release/make_release.sh	Thu Jun 04 14:53:02 2020 +0200
@@ -121,7 +121,7 @@
     echo "Updating sources / Reverting changes"
     cd $FLYS_SOURCE_DIR
     for repo in $REPOS; do
-        cd $repo && hg purge && hg revert -a && hg pull -u && cd -
+        cd $repo && hg revert -a && hg pull -u && cd -
     done;
 fi