Sample calibration state rather than 50/50 boolean

Change to 1/8 chance. So that it will try more shifts. It does not shift
when xaxis is uncalibrated.

spectrum_overload/test/test_Spectrum.py

@@ -164,11 +164,15 @@ def test_wav_select_example():
 
 
 @given(st.lists(st.floats(min_value=1e-6, allow_infinity=False), min_size=1),
-       st.floats(min_value=1e-8), st.booleans(), st.booleans())
+       st.floats(min_value=1e-8), st.sampled_from((1, 1, 1, 1, 1, 1, 1, 0)),
+       st.booleans())
 def test_doppler_shift_with_hypothesis(x, RV, calib, RV_dir):
     """Test doppler shift properties.
-    Need to check values against pyastronomy separately """
-
+    Need to check values against pyastronomy separately 
+
+    calib is sampled with a 1/8 chance being uncalibrated.
+    """
+
     # Added a min value to RV shift to avoid very small RV values (1e-300).
     # Have added a flag to change RV direction to explore negative values
     rvdir = 2 * RV_dir - 1   # True -> 1 , False -> -1