Fixed #24257 -- Corrected i18n handling of percent signs.

Refactored tests to use a sample project.

Updated extraction:
* Removed special handling of single percent signs.
* When extracting messages from template text, doubled all percent signs
  so they are not interpreted by gettext as string format flags. All
  strings extracted by gettext, if containing a percent sign, will now
  be labeled "#, python-format".

Updated translation:
* Used "%%" for "%" in template text before calling gettext.
* Updated {% trans %} rendering to restore "%" from "%%".

3 files changed, 13 insertions, 5 deletions

diff --git a/django/template/base.py b/django/template/base.py
index 71a97fda80..f15f8a6ff6 100644
--- a/django/template/base.py
+++ b/django/template/base.py
@@ -825,10 +825,13 @@ class Variable(object):
             # We're dealing with a literal, so it's already been "resolved"
             value = self.literal
         if self.translate:
+            is_safe = isinstance(value, SafeData)
+            msgid = value.replace('%', '%%')
+            msgid = mark_safe(msgid) if is_safe else msgid
             if self.message_context:
-                return pgettext_lazy(self.message_context, value)
+                return pgettext_lazy(self.message_context, msgid)
             else:
-                return ugettext_lazy(value)
+                return ugettext_lazy(msgid)
         return value
 
     def __repr__(self):
diff --git a/django/templatetags/i18n.py b/django/templatetags/i18n.py
index 4e77aaece4..050ef2c741 100644
--- a/django/templatetags/i18n.py
+++ b/django/templatetags/i18n.py
@@ -7,6 +7,7 @@ from django.template import Library, Node, TemplateSyntaxError, Variable
 from django.template.base import TOKEN_TEXT, TOKEN_VAR, render_value_in_context
 from django.template.defaulttags import token_kwargs
 from django.utils import six, translation
+from django.utils.safestring import SafeData, mark_safe
 
 register = Library()
 
@@ -86,6 +87,11 @@ class TranslateNode(Node):
                 self.message_context.resolve(context))
         output = self.filter_expression.resolve(context)
         value = render_value_in_context(output, context)
+        # Restore percent signs. Percent signs in template text are doubled
+        # so they are not interpreted as string format flags.
+        is_safe = isinstance(value, SafeData)
+        value = value.replace('%%', '%')
+        value = mark_safe(value) if is_safe else value
         if self.asvar:
             context[self.asvar] = value
             return ''
diff --git a/django/utils/translation/trans_real.py b/django/utils/translation/trans_real.py
index 8a2527022d..e05b5613a5 100644
--- a/django/utils/translation/trans_real.py
+++ b/django/utils/translation/trans_real.py
@@ -534,7 +534,6 @@ block_re = re.compile(r"""^\s*blocktrans(\s+.*context\s+((?:"[^"]*?")|(?:'[^']*?
 endblock_re = re.compile(r"""^\s*endblocktrans$""")
 plural_re = re.compile(r"""^\s*plural$""")
 constant_re = re.compile(r"""_\(((?:".*?")|(?:'.*?'))\)""")
-one_percent_re = re.compile(r"""(?<!%)%(?!%)""")
 
 
 def templatize(src, origin=None):
@@ -631,7 +630,7 @@ def templatize(src, origin=None):
                 else:
                     singular.append('%%(%s)s' % t.contents)
             elif t.token_type == TOKEN_TEXT:
-                contents = one_percent_re.sub('%%', t.contents)
+                contents = t.contents.replace('%', '%%')
                 if inplural:
                     plural.append(contents)
                 else:
@@ -667,7 +666,7 @@ def templatize(src, origin=None):
                         g = g.strip('"')
                     elif g[0] == "'":
                         g = g.strip("'")
-                    g = one_percent_re.sub('%%', g)
+                    g = g.replace('%', '%%')
                     if imatch.group(2):
                         # A context is provided
                         context_match = context_re.match(imatch.group(2))