HG indexing fails with "not found in manifest!" error

Due to http://mercurial.selenic.com/bts/issue2699, we can look for a manifest entry of a file that is not in the manifest of where the filectx was created.

The fix is to check for this and avoid that lookup - fixed for the .hgsubstate bug, but could come up in other cases.

Repository index failed due to error com.cenqua.fisheye.rep.RepositoryClientException: com.atlassian.fisheye.dvcs.handler.DvcsProcessException: Error while communicating with VCS: abort: .hgsubstate@cb95ab638b7c: not found in manifest! com.atlassian.fisheye.dvcs.handler.DvcsProcessException: Error while communicating with VCS: abort: .hgsubstate@cb95ab638b7c: not found in manifest! com.atlassian.utils.process.ProcessException: While executing: "hg --config extensions.felog=/opt/j2ee/containers/crucible/builds/fecru-2.6.0-M1-20110301-1721/python/hg/hgfelog/hgfelog.py --config ui.verbose=false felog 51e8e7f3c710eca0df68059ec2bac3520930c65e -p -m " com.atlassian.utils.process.ProcessException: Non-zero exit code: 255