Merge branch 'mk/http-backend-content-length'

The http-backend (used for smart-http transport) used to slurp the whole input until EOF, without paying attention to CONTENT_LENGTH that is supplied in the environment and instead expecting the Web server to close the input stream. This has been fixed. * mk/http-backend-content-length: t5562: avoid non-portable "export FOO=bar" construct http-backend: respect CONTENT_LENGTH for receive-pack http-backend: respect CONTENT_LENGTH as specified by rfc3875 http-backend: cleanup writing to child process