tests/test-excessive-merge

patch: support diff data loss detection and upgrade

In worst case, generating diff in upgrade mode can be two times more expensive
than generating it in git mode directly: we may have to regenerate the whole
diff again whenever a git feature is detected. Also, the first diff attempt is
completely buffered instead of being streamed. That said, even without having
profiled it yet, I am convinced we can fast-path the upgrade mode if necessary
were it to be used in regular diff commands, and not only in mq where avoiding
data loss is worth the price.

#!/bin/sh

hg init

echo foo > a
echo foo > b
hg add a b

hg ci -m "test" -d "1000000 0"

echo blah > a

hg ci -m "branch a" -d "1000000 0"

hg co 0

echo blah > b

hg ci -m "branch b" -d "1000000 0"
HGMERGE=true hg merge 1

hg ci -m "merge b/a -> blah" -d "1000000 0"

hg co 1
HGMERGE=true hg merge 2
hg ci -m "merge a/b -> blah" -d "1000000 0"

hg log
hg debugindex .hg/store/00changelog.i

echo

echo 1
hg manifest --debug 1
echo 2
hg manifest --debug 2
echo 3
hg manifest --debug 3
echo 4
hg manifest --debug 4

echo

hg debugindex .hg/store/data/a.i

hg verify