ckssh.py: ckcommand() now uses source instead of eval

`eval $(cat file)` doesn't work on multi-line output since all the
lines are concatenated to one; simply doing a `source file` fixes
this. (It could also be fixed by adding semicolons to the end of each
line written to eval-file, but that's more complex and doesn't provide
any gain.)

`eval $(ckssh.py bash-init)` does work because, though it's multi-line
output, it does use semicolon separation. This can't so easily be
changed however because `source` works only on files and we don't want
to have to make the user create a temp file to do the bash-init.

Author: 0cjs

bin/ckssh.py

@@ -213,7 +213,7 @@ def print_bash_init(_args, _env):
             local retval=0;
             local evalfile=$(mktemp -t ckssh-eval-XXXXX);
             ''' + me + ''' --eval-file "$evalfile" "$@"; retval=$?;
-            eval $(cat "$evalfile");
+            source "$evalfile";
             rm -f "$evalfile";
             return $retval;
         };