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.

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adding bar

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adding foo

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adding bomb

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adding a.c

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adding dir/a.o

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adding dir/b.o

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M dir/b.o

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! a.c

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! dir/a.o

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? .hgignore

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a.c: unsupported file type (type is fifo)

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! a.c

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# test absolute path through symlink outside repo

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A f

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# try symlink outside repo to file inside

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abort: ../z not under root

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# try cloning symlink in a subdir

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1. commit a symlink

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? a/b/c/demo

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adding a/b/c/demo

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2. clone it

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1 files updated, 0 files merged, 0 files removed, 0 files unresolved

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# git symlink diff

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diff --git a/a/b/c/demo b/a/b/c/demo

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new file mode 120000

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--- /dev/null

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+++ b/a/b/c/demo

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@@ -0,0 +1,1 @@

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+/path/to/symlink/source

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\ No newline at end of file

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# import git symlink diff

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applying ../sl.diff

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diff --git a/a/b/c/demo b/a/b/c/demo

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new file mode 120000

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--- /dev/null

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+++ b/a/b/c/demo

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@@ -0,0 +1,1 @@

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+/path/to/symlink/source

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\ No newline at end of file