Thousands separator in formatting was handled differently than for floats etc.

See python/cpython#131067

Author: scoder

src/quicktions.pyx

@@ -994,6 +994,9 @@ cdef class Fraction:
         cdef bint trim_point = not alternate_form
         exponent_indicator = "E" if presentation_type in u"EFG" else "e"
 
+        if align == '=' and fill == '0':
+            zeropad = True
+
         cdef bint negative, scientific
         cdef Py_ssize_t exponent, figures
 

src/test_fractions.py

@@ -1688,11 +1688,8 @@ def test_format_f_presentation_type(self):
             (F('-1234.5678'), '08,.0f', '-001,235'),
             (F('-1234.5678'), '09,.0f', '-0,001,235'),
             # Corner-case - zero-padding specified through fill and align
-            # instead of the zero-pad character - in this case, treat '0' as a
-            # regular fill character and don't attempt to insert commas into
-            # the filled portion. This differs from the int and float
-            # behaviour.
-            (F('1234.5678'), '0=12,.2f', '00001,234.57'),
+            # instead of the zero-pad character.
+            (F('1234.5678'), '0=12,.2f', '0,001,234.57'),
             # Corner case where it's not clear whether the '0' indicates zero
             # padding or gives the minimum width, but there's still an obvious
             # answer to give. We want this to work in case the minimum width