Sigh. The ubiquitous utility less does a really bad and hard to understand
thing. For some time now, it behaves not just as a reader but also a writer:
it writes a history file (specified by the environment variable LESSHISTFILE
which is $HOME/.lesshst by default). If you want less to be writing
things, fine, but don't force it on me! This has caused some annoying
problems that have been really hard to finally trace back to less.