vcs: fix get_file_annotate - consistently bind sha so it has the right value when executing The Git implementation did *not* save the sha value in the lambda expression for the "changeset lazy loader". Thus, if the generator had moved on and assigned a different value to sha when the expression was executed, it would use the "wrong" sha. Fixed by doing as the Hg implementation: bind the sha value as value of a default parameter when defining the lambda expression. The Hg implementation did however also save the line - it is not used, and there is no need for that.

# requirements.txt file for use as "pip install -r requirements.txt" as a
# readthedocs compatible alternative to "pip install -e ." which is a working
# alternative to "setup.py develop" which doesn't work with Mercurial 3.7
.