Went through 60 python packages to see which fails installing on the serve. Took hrs as I have no terminal access but just via jenkins pipeline. So "edit/gitpush requirements.txt and wait" many times. Eventually looped them 1 by 1 in shell. By end of day got the list that installs.
Finally sent the whole list....with confidence
-Takes full 10 mins & Fails......
(panic mode starts)
+Changed the sequence = fails, somewhere else
+1 by 1 again = installs.....
+few random without the culprit =works
+again, whole list = fails, somewhere else

Need to sleep, brain's thinking of eagles