gh-38824: Turn some doctests in `ell_rational_field.py` into long tests
    
Fixes #38813

Some of the doctests in `ell_rational_field.py` ran into RuntimeErrors
and couldn't compute generators in time, causing tests to fail. Turning
them into long tests (which is necessary since they have to run longer
in some cases) fixes that problem.

Also added some missing spaces.
    
URL: #38824
Reported by: Sebastian A. Spindler
Reviewer(s): Frédéric Chapoton, Sebastian A. Spindler

Author: Release Manager

src/sage/schemes/elliptic_curves/ell_rational_field.py

@@ -444,7 +444,7 @@ def mwrank(self, options=''):
         EXAMPLES::
 
             sage: E = EllipticCurve('37a1')
-            sage: E.mwrank() #random
+            sage: E.mwrank() # random
             ...
             sage: print(E.mwrank())
             Curve [0,0,1,-1,0] :        Basic pair: I=48, J=-432
@@ -2335,7 +2335,7 @@ def gens(self, proof=None, **kwds):
              over Rational Field
             sage: E1.gens() # random (if database not used)
             [(-400 : 8000 : 1), (0 : -8000 : 1)]
-            sage: E1.gens(algorithm='pari')   #random
+            sage: E1.gens(algorithm='pari')   # random
             [(-400 : 8000 : 1), (0 : -8000 : 1)]
 
         TESTS::
@@ -2353,6 +2353,13 @@ def gens(self, proof=None, **kwds):
             sage: P = E.lift_x(10/9)
             sage: set(E.gens()) <= set([P,-P])
             True
+
+        Check that :issue:`38813` has been fixed:
+
+            sage: set_random_seed(91390048253425197917505296851335255685)
+            sage: E = EllipticCurve([-127^2,0])
+            sage: E.gens(use_database=False, algorithm='pari', pari_effort=4)   # long time
+            [(611429153205013185025/9492121848205441 : 15118836457596902442737698070880/924793900700594415341761 : 1)]
         """
         if proof is None:
             from sage.structure.proof.proof import get_flag
@@ -2405,14 +2412,15 @@ def _compute_gens(self, proof,
             True
 
             sage: E = EllipticCurve([-127^2,0])
-            sage: E.gens(use_database=False, algorithm='pari',pari_effort=4)   # random
+            sage: E.gens(use_database=False, algorithm='pari', pari_effort=4)   # long time, random
             [(611429153205013185025/9492121848205441 : 15118836457596902442737698070880/924793900700594415341761 : 1)]
 
         TESTS::
 
+            sage: E = EllipticCurve([-127^2,0])
             sage: P = E.lift_x(611429153205013185025/9492121848205441)
-            sage: ge = set(E.gens(use_database=False, algorithm='pari',pari_effort=4))
-            sage: ge <= set([P+T for T in E.torsion_points()]
+            sage: ge = set(E.gens(use_database=False, algorithm='pari',pari_effort=4))   # long time
+            sage: ge <= set([P+T for T in E.torsion_points()]  # long time
             ....:        + [-P+T for T in E.torsion_points()])
             True
         """