splicemap: improve error handling when source is hg (
issue2084)
1. Introduced 2 levels of error handling for splicemap files
a. Check the splicemap file for rules which are same across different
types of source repos. This is done through enhancing parsesplicemap
function
b. Check revision string formats. Each repo may have their own format.
This is done usign checkrevformat function
c. Implemented the above two for hg
splicemap: move parsesplicemap to convcmd.py (
issue2084)
parsesplicemap is only referenced from convcmd.py
This move is necessary to enable other changes related to
this issue
tests: skip permissions tests in test-phases-exchange when fs lacks permissions