hgweb: reuse body file object when hgwebdir calls hgweb (issue5851) An unintended side-effect of f0a851542a05 was that the request body file object (which uses a util.cappedreader) was constructed twice when hgwebdir called into hgweb. Since we attempt to read all remaining data from this file object when Content-Length is defined and since there were two instances of this object and the client supplied no additional data to read, this resulted in deadlock. The fix implemented in this commit is to reuse the request body file object when it is passed from hgwebdir to hgweb. A test demonstrating `hg clone` and `hg push` via hgwebdir has been added. Without this patch, the test hangs when doing `hg clone`. Surprisingly, this must mean that we have effectively no test coverage of the wire protocol when run via hgwebdir. Differential Revision: https://phab.mercurial-scm.org/D3427