Do not fail if reldst == relsrc

Defining same reldst as relsrc is useless, but does not harm, so we can
let it slip through.

src/include/release.sh

     #
     local rlevel=$1     # release level (x, y or z)
     local newtag        # new tag
+    local relsrc        # release source branch (if any)
     local reldst        # release destination branch (if any)
 
     _relck git_present
     $MKIT_DRY && return
     git tag -m "$(_release_msg)" "$newtag"
 
+    relsrc=$(ini 1value project:relsrc)
     reldst=$(ini 1value project:reldst)
-    debug_var reldst
-    if test -n "$reldst"; then
+    debug_var relsrc reldst
+    if test -n "$reldst" && test "$reldst" != "$relsrc"; then
         git branch -f "$reldst" "$newtag"
     fi
 }