hg: use vfs functions in clone
This change applies vfs functions in clone. destvfs.exists will invoke
os.path.lexists via lexists of vfs to check for broken symbolic links.
hgterm,
am, km, mir, msgr, xenl,
colors#8, cols#80, it#8, lines#24, pairs#64,
acsc=``aaffggiijjkkllmmnnooppqqrrssttuuvvwwxxyyzz{{||}}~~,
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cup=\E[%i%p1%d;%p2%dH, cuu=\E[%p1%dA, cuu1=\E[A,
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ed=\E[J, el=\E[K, enacs=\E)0, home=\E[H, ht=\t,
hts=\EH, il=\E[%p1%dL, il1=\E[L, ind=\n,
is2=\E[m\E[?7h\E[4l\E>\E7\E[r\E[?1;3;4;6l\E8, kbs=\b,
kcub1=\EOD, kcud1=\EOB, kcuf1=\EOC, kcuu1=\EOA,
kdch1=\E[3~, kf1=\E[11~, kf10=\E[21~, kf11=\E[23~,
kf12=\E[24~, kf13=\E[25~, kf14=\E[26~, kf15=\E[28~,
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kf5=\E[15~, kf6=\E[17~, kf7=\E[18~, kf8=\E[19~,
kf9=\E[20~, kfnd=\E[1~, kich1=\E[2~, kmous=\E[M,
knp=\E[6~, kpp=\E[5~, kslt=\E[4~, op=\E[m, rc=\E8,
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smacs=^N, smcup=\E7\E[?47h, smir=\E[4h,
smkx=\E[?1h\E=, smso=\E[7m, smul=\E[4m, tbc=\E[3g,
u6=\E[%i%d;%dR, u7=\E[6n, u8=\E[?1;2c, u9=\E[c,