Log Message:
Update serf0 to 0.7.2.

Serf 0.7.2 [2011-03-12, branch 0.7.x r1451]
  Actually disable Nagle when creating a connection (r1441).
  Return error when app asks for HTTPS over proxy connection (r1433).

Serf 0.7.1 [2011-01-25, branch 0.7.x r1431]
  Fix memory leak when using SSL (r1408, r1416).
  Fix build for blank apr-util directory (r1421).

Serf 0.7.0 [2010-08-25, r1407]
  Fix double free abort when destroying request buckets.
  Fix test server in unit test framework to avoid random test failures.
  Allow older Serf programs which don't use the new authn framework to still
    handle authn without forcing them to switch to the new framework. (r1401)
  Remove the SERF_DECLARE macros, preferring a .DEF file for Windows
  Barrier buckets now pass read_iovec to their wrapped bucket.
  Fix HTTP header parsing to allow for empty header values.

Serf 0.6.1 [2010-05-14, r1370]
  Generally: this release fixes problems with the 0.4.0 packaging.
  Small compilation fix in outgoing.c for Windows builds.

Serf 0.6.0 [2010-05-14, r1363]
  Not released.

Serf 0.5.0
  Not released.

Serf 0.4.0 [2010-05-13, r1353]
  [NOTE: this release misstated itself as 0.5.0; use a later release instead]

  Provide authn framework, supporting Basic, Digest, Kerberos (SSPI, GSS),
    along with proxy authn using Basic or Digest
  Added experimental listener framework, along with test_server.c
  Improvements and fixes to SSL support, including connection setup changes
  Experimental support for unrequested, arriving ("async") responses
  Experimental BWTP support using the async arrival feature
  Headers are combined on read (not write), to ease certian classes of parsing
  Experimental feature on aggregate buckets for a callback-on-empty
  Fix the bucket allocator for when APR is using its pool debugging features
  Proxy support in the serf_get testing utility
  Fix to include the port number in the Host header
  serf_get propagates errors from the response, instead of aborting (Issue 52)
  Added serf_lib_version() for runtime version tests

Serf 0.3.1 [2010-02-14, r1320]
  Fix loss of error on request->setup() callback. (Issue 47)
  Support APR 2.x. (Issue 48)
  Fixed slowdown in aggregate bucket with millions of child buckets.
  Avoid hang in apr_pollset_poll() by unclosed connections after fork().