In the spirit of similar changes for FSFS in r34951, avoid SEGFAULTs caused by trying to get/set a 'checksum-rep' record when no SHA1 checksum is available.
In the spirit of similar changes for FSFS in r34951, avoid SEGFAULTs
caused by trying to get/set a 'checksum-rep' record when no SHA1
checksum is available.

* subversion/libsvn_fs_base/dag.c
  (maybe_store_checksum_rep): Only try to record checksum->rep
    mappings when there's a SHA1 checksum available for use.


git-svn-id: f8a4e5e023278da1e04e203c7fe051e3c4285d88@875106 13f79535-47bb-0310-9956-ffa450edef68

wbond/subversion,wbond/subversion,wbond/subversion,wbond/subversion,YueLinHo/Subversion,YueLinHo/Subversion,wbond/subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,wbond/subversion,wbond/subversion,YueLinHo/Subversion,YueLinHo/Subversion