We're seeing tracebacks from buildhistory analysing the python 3.8 -> 3.9
upgrade due to the significant file renames. Avoid these by checking before
removal as they can happen multiple times.
(From OE-Core rev: b1eb390bbcb995c0da70478e17f9170721c75341)
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>