Made ipdb optional.

requirements.txt

@@ -2,3 +2,4 @@ django<2
 python-dateutil
 beautifulsoup4
 translitcodec
+# ipdb

utils/templatetags/debug_utils.py

@@ -2,19 +2,23 @@
 from __future__ import unicode_literals
 # Erik Stein <code@classlibrary.net>, 2009-2017
 
-import ipdb
-from django import template
+try:
+    import ipdb
+    from django import template
 
 
-register = template.Library()
+    register = template.Library()
 
 
-@register.filter
-def ipdb_inspect(value):
+    @register.filter
+    def ipdb_inspect(value):
         ipdb.set_trace()
         return value
 
 
-@register.simple_tag
-def ipdb_set_breakpoint():
+    @register.simple_tag
+    def ipdb_set_breakpoint():
         ipdb.set_trace()
+
+except:
+    pass