convert: add a mode where mercurial_sink skips empty revisions. The getchanges function of some converter_source classes can return some false positives. I.e. they sometimes claim that a file "foo" was changed in some revision, even though its contents are still the same. convert_svn is particularly bad, but I think this can also happen with convert_cvs and, at least in theory, with mercurial_source. For regular conversions this is not really a problem - as long as getfile returns the right contents, we'll get a converted revision with the right contents. But when we use --filemap, this could lead to superfluous revisions being converted. Instead of fixing every converter_source, I decided to change mercurial_sink to work around this problem. When --filemap is used, we're interested only in revisions that touch some specific files. If a revision doesn't change any of these files, then we're not interested in it (at least for revisions with a single parent; merges are special). For mercurial_sink, we abuse this property and rollback a commit if the manifest text hasn't changed. This avoids duplicating the logic from localrepo.filecommit to detect unchanged files.

#!/bin/sh

mkdir a
cd a
hg init
echo foo > t1
hg add t1
hg commit -m "1" -d "1000000 0"

cd ..
hg clone a b

cd a
echo foo > t2
hg add t2
hg commit -m "2" -d "1000000 0"

cd ../b
echo foo > t3
hg add t3
hg commit -m "3" -d "1000000 0"

hg push ../a
hg pull ../a
hg push ../a
hg merge
hg commit -m "4" -d "1000000 0"
hg push ../a
cd ..

hg init c
cd c
for i in 0 1 2; do
    echo $i >> foo
    hg ci -Am $i -d "1000000 0"
done
cd ..

hg clone c d
cd d
for i in 0 1; do
    hg co -C $i
    echo d-$i >> foo
    hg ci -m d-$i -d "1000000 0"
done

HGMERGE=true hg merge 3
hg ci -m c-d -d "1000000 0"

hg push ../c; echo $?
hg push -r 2 ../c; echo $?
hg push -r 3 ../c; echo $?
hg push -r 3 -r 4 ../c; echo $?
hg push -f -r 3 -r 4 ../c; echo $?
hg push -r 5 ../c; echo $?

# issue 450
hg init ../e
hg push -r 0 ../e ; echo $?
hg push -r 1 ../e ; echo $?

exit 0