HG: Missing clone causes failure on startup

If the clone is missing when FishEye starts up, the scanner gets a failure in HgLinecountCalculator$HgChangesetLinecountCalculator.processBranchPoint and fails to start.
Error keeps recurring.

This happens when restoring demotions.

We need to have a check for a missing clone before this process commences.

Stack:

[java] 12:25:57 INFO - starting initial scan of repository fe-hg-convert
[java] 12:25:57 ERROR - Exception during slurp
[java] com.cenqua.fisheye.rep.DbException: com.atlassian.fisheye.dvcs.handler.DvcsProcessException: Error while communicating with VCS:
[java] at com.atlassian.fisheye.hg.HgLinecountCalculator$HgChangesetLinecountCalculator.processBranchPoint(HgLinecountCalculator.java:48)
[java] at com.atlassian.fisheye.hg.HgLinecountCalculator$HgChangesetLinecountCalculator.indexChangeset(HgLinecountCalculator.java:88)
[java] at com.cenqua.fisheye.rep.BaseLinecountCalculator$1.visit(BaseLinecountCalculator.java:86)
[java] at com.cenqua.fisheye.infinitydb.UniqueStringTable.visit(UniqueStringTable.java:207)
[java] at com.cenqua.fisheye.infinitydb.UniqueStringTable.visit(UniqueStringTable.java:193)
[java] at com.cenqua.fisheye.cache.BaseRevisionCache.visitChangesetIds(BaseRevisionCache.java:610)
[java] at com.cenqua.fisheye.rep.BaseLinecountCalculator.indexChangesets(BaseLinecountCalculator.java:83)
[java] at com.cenqua.fisheye.rep.BaseLinecountCalculator.calcBlame(BaseLinecountCalculator.java:56)
[java] at com.cenqua.fisheye.rep.impl.UpgradeDataFilenameSearch.initAndUpgradeBuckets(UpgradeDataFilenameSearch.java:87)
[java] at com.cenqua.fisheye.rep.BaseRepositoryScanner.upgradeSearchData(BaseRepositoryScanner.java:468)
[java] at com.cenqua.fisheye.rep.BaseRepositoryScanner.ping(BaseRepositoryScanner.java:173)
[java] at com.cenqua.fisheye.rep.BaseRepositoryEngine.doSlurp(BaseRepositoryEngine.java:85)
[java] at com.cenqua.fisheye.rep.RepositoryEngine.slurp(RepositoryEngine.java:382)
[java] at com.cenqua.fisheye.rep.ping.OneOffPingRequest.doRequest(OneOffPingRequest.java:25)
[java] at com.cenqua.fisheye.rep.ping.PingRequest.process(PingRequest.java:66)
[java] at com.cenqua.fisheye.rep.RepositoryHandle.processPingRequests(RepositoryHandle.java:127)
[java] at com.cenqua.fisheye.rep.RepositoryHandle.queuePingRequest(RepositoryHandle.java:117)
[java] at com.cenqua.fisheye.rep.ping.PingRequest.run(PingRequest.java:33)
[java] at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
[java] at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
[java] at java.lang.Thread.run(Thread.java:637)
[java] Caused by: com.atlassian.fisheye.dvcs.handler.DvcsProcessException: Error while communicating with VCS:
[java] at com.atlassian.fisheye.dvcs.client.DvcsContext.executeCommand(DvcsContext.java:172)
[java] at com.atlassian.fisheye.hg.HgCache.visitExtantFileRevisions(HgCache.java:149)
[java] at com.atlassian.fisheye.hg.HgLinecountCalculator$HgChangesetLinecountCalculator.processBranchPoint(HgLinecountCalculator.java:35)
[java] ... 20 more
[java] Caused by: com.atlassian.utils.process.ProcessException: While executing: "hg --config extensions.felog=/Users/mwatson/work/crucible/trunk/output/dist/python/hg/hgfelog/hgfelog.py -v feparents e4e32b7db7347beb409613d7e7ec020b6e5e1b80"
[java] at com.atlassian.fisheye.dvcs.client.DvcsContext.executeCommand(DvcsContext.java:207)
[java] at com.atlassian.fisheye.dvcs.client.DvcsContext.executeCommand(DvcsContext.java:190)
[java] at com.atlassian.fisheye.dvcs.client.DvcsContext.executeCommand(DvcsContext.java:170)
[java] ... 22 more
[java] Caused by: com.atlassian.utils.process.ProcessException: java.io.IOException: Cannot run program "hg" (in directory "/Users/mwatson/work/crucible/trunk/output/dist_inst/var/cache/fe-hg-convert/clone"): error=2, No such file or directory
[java] at com.atlassian.utils.process.ExternalProcess.start(ExternalProcess.java:157)
[java] at com.atlassian.utils.process.ExternalProcess.execute(ExternalProcess.java:266)
[java] at com.atlassian.fisheye.dvcs.client.DvcsContext.executeCommand(DvcsContext.java:218)
[java] at com.atlassian.fisheye.dvcs.client.DvcsContext.executeCommand(DvcsContext.java:200)
[java] ... 24 more
[java] Caused by: java.io.IOException: Cannot run program "hg" (in directory "/Users/mwatson/work/crucible/trunk/output/dist_inst/var/cache/fe-hg-convert/clone"): error=2, No such file or directory
[java] at java.lang.ProcessBuilder.start(ProcessBuilder.java:460)
[java] at java.lang.Runtime.exec(Runtime.java:593)
[java] at com.atlassian.utils.process.ExternalProcess.start(ExternalProcess.java:154)
[java] ... 27 more
[java] Caused by: java.io.IOException: error=2, No such file or directory
[java] at java.lang.UNIXProcess.forkAndExec(Native Method)
[java] at java.lang.UNIXProcess.<init>(UNIXProcess.java:53)
[java] at java.lang.ProcessImpl.start(ProcessImpl.java:91)
[java] at java.lang.ProcessBuilder.start(ProcessBuilder.java:453)
[java] ... 29 more