Speedup FastText tests (#1686)

Current version of FastText is pure-python,
so CPU-bound processing with multiple workers in it is a bad idea.
Using workers=12 in a some tests increased execution time of tests.

gensim/test/test_fasttext.py

@@ -368,7 +368,7 @@ def test_cbow_hs_against_wrapper(self):
 
         model_gensim = FT_gensim(size=50, sg=0, cbow_mean=1, alpha=0.05, window=5, hs=1, negative=0,
             min_count=5, iter=5, batch_words=1000, word_ngrams=1, sample=1e-3, min_n=3, max_n=6,
-            sorted_vocab=1, workers=12, min_alpha=0.0)
+            sorted_vocab=1, workers=1, min_alpha=0.0)
 
         lee_data = LineSentence(datapath('lee_background.cor'))
         model_gensim.build_vocab(lee_data)
@@ -388,7 +388,7 @@ def test_sg_hs_against_wrapper(self):
 
         model_gensim = FT_gensim(size=50, sg=1, cbow_mean=1, alpha=0.025, window=5, hs=1, negative=0,
             min_count=5, iter=5, batch_words=1000, word_ngrams=1, sample=1e-3, min_n=3, max_n=6,
-            sorted_vocab=1, workers=12, min_alpha=0.0)
+            sorted_vocab=1, workers=1, min_alpha=0.0)
 
         lee_data = LineSentence(datapath('lee_background.cor'))
         model_gensim.build_vocab(lee_data)
@@ -444,22 +444,22 @@ def online_sanity(self, model):
 
     @unittest.skipIf(IS_WIN32, "avoid memory error with Appveyor x32")
     def test_sg_hs_online(self):
-        model = FT_gensim(sg=1, window=2, hs=1, negative=0, min_count=3, iter=1, seed=42, workers=12)
+        model = FT_gensim(sg=1, window=2, hs=1, negative=0, min_count=3, iter=1, seed=42, workers=1)
         self.online_sanity(model)
 
     @unittest.skipIf(IS_WIN32, "avoid memory error with Appveyor x32")
     def test_sg_neg_online(self):
-        model = FT_gensim(sg=1, window=2, hs=0, negative=5, min_count=3, iter=1, seed=42, workers=12)
+        model = FT_gensim(sg=1, window=2, hs=0, negative=5, min_count=3, iter=1, seed=42, workers=1)
         self.online_sanity(model)
 
     @unittest.skipIf(IS_WIN32, "avoid memory error with Appveyor x32")
     def test_cbow_hs_online(self):
-        model = FT_gensim(sg=0, cbow_mean=1, alpha=0.05, window=2, hs=1, negative=0, min_count=3, iter=1, seed=42, workers=12)
+        model = FT_gensim(sg=0, cbow_mean=1, alpha=0.05, window=2, hs=1, negative=0, min_count=3, iter=1, seed=42, workers=1)
         self.online_sanity(model)
 
     @unittest.skipIf(IS_WIN32, "avoid memory error with Appveyor x32")
     def test_cbow_neg_online(self):
-        model = FT_gensim(sg=0, cbow_mean=1, alpha=0.05, window=2, hs=0, negative=5, min_count=5, iter=1, seed=42, workers=12, sample=0)
+        model = FT_gensim(sg=0, cbow_mean=1, alpha=0.05, window=2, hs=0, negative=5, min_count=5, iter=1, seed=42, workers=1, sample=0)
         self.online_sanity(model)