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

# This runs with TZ="GMT"
hg init
echo "test-parse-date" > a
hg add a
hg ci -d "2006-02-01 13:00:30" -m "rev 0"
echo "hi!" >> a
hg ci -d "2006-02-01 13:00:30 -0500" -m "rev 1"
hg tag -d "2006-04-15 13:30" "Hi"
hg backout --merge -d "2006-04-15 13:30 +0200" -m "rev 3" 1
hg ci -d "1150000000 14400" -m "rev 4 (merge)"
echo "fail" >> a
hg ci -d "should fail" -m "fail"
hg ci -d "100000000000000000 1400" -m "fail"
hg ci -d "100000 1400000" -m "fail"

# Check with local timezone other than GMT and with DST
TZ="PST+8PDT"
export TZ
# PST=UTC-8 / PDT=UTC-7
hg debugrebuildstate
echo "a" > a
hg ci -d "2006-07-15 13:30" -m "summer@UTC-7"
hg debugrebuildstate
echo "b" > a
hg ci -d "2006-07-15 13:30 +0500" -m "summer@UTC+5"
hg debugrebuildstate
echo "c" > a
hg ci -d "2006-01-15 13:30" -m "winter@UTC-8"
hg debugrebuildstate
echo "d" > a
hg ci -d "2006-01-15 13:30 +0500" -m "winter@UTC+5"
hg log --template '{date|date}\n'