By William James and Guy Faulconbridge LONDON (Reuters) – Britain will stop Russia selling sovereign debt in London after President Vladimir Putin deployed military forces into two breakaway regions of eastern Ukraine, Foreign Secretary Liz Truss said on Wednesday. The move is in line with other incremental steps Western countries have taken this week to punish Russia for its actions in Ukraine, stopping short of comprehensive sanctions threatened in case of a large-scale assault. On Tuesday, Britain added to its sanctions list five small Russian banks and three Russian billionaires already sa…