Created attachment 142239 [details]
Git diff specifying 2 commits (GD is aliased to git diff)

(High severity because laptop is useless when travelling)
With HDMI unplugged, X laptop screen is black with only a cursor. Cursor
changes shape as it moves over xterm windows put there by xinitrc.
Bisecting in git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git finds
2bfb0b678e48dee76543bfa2079b7e42609332fb has the problem but adjacent commit
9c24c10a2c1e1bb478b6bb70612d9e885aee044f does not.
There is an oddity with git diff between these two: git diff <commit1>
<commit2> produces copious output and a git warning (see attachment), but git
checkout <commit2>; git diff <commit1> only shows one patched file (next
attachment). You might want to try this - I re-cloned the repo in case the old
one was corrupted but it made no difference.