precheck: fix false warning about content-divergence creation
Before this patch, if we try to `hg prune` (without any successors) an
already obsoleted cset which has at least one successor, it would false
warn about new content-divergence. As we know, pruning cset without any
successors can not create any divergence.
Differential Revision: https://phab.mercurial-scm.org/D12002
#require no-windows
$ . "$TESTDIR/remotefilelog-library.sh"
$ hg init master
$ cd master
$ cat >> .hg/hgrc <<EOF
> [remotefilelog]
> server=True
> EOF
$ echo x > x
$ echo y > y
$ echo z > z
$ hg commit -qAm xy
$ cd ..
$ hgcloneshallow ssh://user@dummy/master shallow -q
3 files fetched over 1 fetches - (3 misses, 0.00% hit ratio) over *s (glob)
$ cd shallow
Verify error message when noc achepath specified
$ hg up -q null
$ cp $HGRCPATH $HGRCPATH.bak
$ grep -v cachepath < $HGRCPATH.bak > tmp
$ mv tmp $HGRCPATH
$ hg up tip
abort: could not find config option remotefilelog.cachepath
[255]
$ mv $HGRCPATH.bak $HGRCPATH
Verify error message when no fallback specified
$ hg up -q null
$ rm .hg/hgrc
$ clearcache
$ hg up tip
3 files fetched over 1 fetches - (3 misses, 0.00% hit ratio) over *s (glob)
abort: no remotefilelog server configured - is your .hg/hgrc trusted?
[255]