pager: add a function in compats to start pager
This will help us enabling pager when ui.pager API exists. Also we can try
plugging in the old pager API in this function and we won't have to change
anything.
$.$TESTDIR/testlib/common.shsetup$cat>>$HGRCPATH<<EOF>[defaults]>fold=-d"0 0">[extensions]>evolve=>[ui]>logtemplate='{rev} - {node|short}{desc|firstline} [{author}] ({phase})\n'>EOF$hginitfold-tests$cdfold-tests/$hgdebugbuilddag.+3:branchpoint+4*branchpoint+2$hgup'desc("r7")'0filesupdated,0filesmerged,0filesremoved,0filesunresolved$hglog-Go10-a8407f9a3dc1r10[debugbuilddag](draft)|o9-529dfc5bb875r9[debugbuilddag](draft)|o8-abf57d94268br8[debugbuilddag](draft)||@7-4de32a90b66cr7[debugbuilddag](draft)|||o6-f69452c5b1afr6[debugbuilddag](draft)|||o5-c8d03c1b5e94r5[debugbuilddag](draft)|||o4-bebd167eb94dr4[debugbuilddag](draft)|/o3-2dc09a01254dr3[debugbuilddag](draft)|o2-01241442b3c2r2[debugbuilddag](draft)|o1-66f7d451a68br1[debugbuilddag](draft)|o0-1ea73414a91br0[debugbuilddag](draft)Testvariouserrorcase$hgfold--exactnull::abort:cannotfoldthenullrevision(nochangesetcheckedout)[255]$hgfoldabort:norevisionsspecified[255]$hgfold--fromabort:norevisionsspecified[255]$hgfold.abort:mustspecifyeither--fromor--exact[255]$hgfold--from.--exactabort:cannotuseboth--fromand--exact[255]$hgfold--from.singlerevisionspecified,nothingtofold[1]$hgfold'0::(7+10)'--exactabort:cannotfoldnon-linearrevisions(multipleheadsgiven)[255]$hgfold-r4-r6--exactabort:cannotfoldnon-linearrevisions(multiplerootsgiven)[255]$hgfold--from101abort:cannotfoldnon-linearrevisions(givenrevisionsareunrelatedtoparentofworkingdirectory)[255]$hgfold--exact-r"4 and not 4"abort:specifiedrevisionsevaluatetoanemptyset(usedifferentrevisionarguments)[255]$hgphase--public0$hgfold--from-r0abort:cannotfoldpublicchangesets:1ea73414a91b(see'hg help phases'fordetails)[255]Testactualfolding$hgfold--from-r'desc("r5")'3changesetsfolded0filesupdated,0filesmerged,0filesremoved,0filesunresolved(testinheritedfromtest-evolve.t)$hgfold--from6#wanttorunhgfold6abort:hiddenrevision'6'!(use--hiddentoaccesshiddenrevisions;successor:198b5c405d01)[255]$hglog-G@11-198b5c405d01r5[debugbuilddag](draft)||o10-a8407f9a3dc1r10[debugbuilddag](draft)|||o9-529dfc5bb875r9[debugbuilddag](draft)|||o8-abf57d94268br8[debugbuilddag](draft)||o|4-bebd167eb94dr4[debugbuilddag](draft)|/o3-2dc09a01254dr3[debugbuilddag](draft)|o2-01241442b3c2r2[debugbuilddag](draft)|o1-66f7d451a68br1[debugbuilddag](draft)|o0-1ea73414a91br0[debugbuilddag](public)testfold--exact$hgfold--exact'desc("r8") + desc("r10")'abort:cannotfoldnon-linearrevisions(multiplerootsgiven)[255]$hgfold--exact'desc("r8")::desc("r10")'3changesetsfolded$hglog-Go12-b568edbee6e0r8[debugbuilddag](draft)||@11-198b5c405d01r5[debugbuilddag](draft)|||o4-bebd167eb94dr4[debugbuilddag](draft)|/o3-2dc09a01254dr3[debugbuilddag](draft)|o2-01241442b3c2r2[debugbuilddag](draft)|o1-66f7d451a68br1[debugbuilddag](draft)|o0-1ea73414a91br0[debugbuilddag](public)Testallowunstable$echoa>a$hgadda$hgcommit'-m r11'$hgup'.^'0filesupdated,0filesmerged,1filesremoved,0filesunresolved$hglog-Go13-14d0e0da8e91r11[test](draft)||o12-b568edbee6e0r8[debugbuilddag](draft)||@|11-198b5c405d01r5[debugbuilddag](draft)||o|4-bebd167eb94dr4[debugbuilddag](draft)|/o3-2dc09a01254dr3[debugbuilddag](draft)|o2-01241442b3c2r2[debugbuilddag](draft)|o1-66f7d451a68br1[debugbuilddag](draft)|o0-1ea73414a91br0[debugbuilddag](public)$cat<<EOF>>.hg/hgrc>[experimental]>evolution=createmarkers,allnewcommands>EOF$hgfold--from'desc("r4")'abort:foldwillorphan1descendants(see'hg help evolution.instability')[255]$hgfold--from'desc("r3")::desc("r11")'abort:foldwillorphan1descendants(see'hg help evolution.instability')[255]test--uservariant$cat<<EOF>>.hg/hgrc>[experimental]>evolution=createmarkers,allnewcommands>EOF$cat<<EOF>>.hg/hgrc>[experimental]>evolution=all>EOF$hgfold--exact'desc("r5") + desc("r11")'--user'Victor Rataxes <victor@rhino.savannah>'2changesetsfolded1filesupdated,0filesmerged,0filesremoved,0filesunresolved$hglog-G@14-29b470a33594r5[VictorRataxes<victor@rhino.savannah>](draft)||o12-b568edbee6e0r8[debugbuilddag](draft)||o|4-bebd167eb94dr4[debugbuilddag](draft)|/o3-2dc09a01254dr3[debugbuilddag](draft)|o2-01241442b3c2r2[debugbuilddag](draft)|o1-66f7d451a68br1[debugbuilddag](draft)|o0-1ea73414a91br0[debugbuilddag](public)$hgfold--from'desc("r4")'-U2changesetsfolded0filesupdated,0filesmerged,0filesremoved,0filesunresolved$hglog-G@15-91880abed0f2r4[test](draft)||o12-b568edbee6e0r8[debugbuilddag](draft)|/o3-2dc09a01254dr3[debugbuilddag](draft)|o2-01241442b3c2r2[debugbuilddag](draft)|o1-66f7d451a68br1[debugbuilddag](draft)|o0-1ea73414a91br0[debugbuilddag](public)$cd..