Index: tools/backup/hot-backup.py.in
===================================================================
--- tools/backup/hot-backup.py.in	(revision 27147)
+++ tools/backup/hot-backup.py.in	(working copy)
@@ -53,7 +53,7 @@
 svnadmin = r"@SVN_BINDIR@/svnadmin"
 
 # Number of backups to keep around (0 for "keep them all")
-num_backups = 64
+num_backups = int(os.environ.get("SVN_HOTBACKUP_BACKUPS_NUMBER", 64))
 
 # Archive types/extensions
 archive_map = {