Merge branch 'jk/diff-CBM'

* jk/diff-CBM:
  diff: report bogus input to -C/-M/-B

diff --cc diff.c
index db5e84443bfe915b5e44ec2fc573ebdb95dd20c1,84876431bc64c72a3e632d40eb8a13d270fc9a56..6991ed4e17343a3104d3fd518b5d85d0913e9259
--- 1/diff.c
--- 2/diff.c
+++ b/diff.c
@@@ -3149,19 -3140,16 +3149,19 @@@ int diff_opt_parse(struct diff_options 
                return stat_opt(options, av);
  
        /* renames options */
 -      else if (!prefixcmp(arg, "-B")) {
 +      else if (!prefixcmp(arg, "-B") || !prefixcmp(arg, "--break-rewrites=") ||
 +               !strcmp(arg, "--break-rewrites")) {
                if ((options->break_opt = diff_scoreopt_parse(arg)) == -1)
-                       return -1;
+                       return error("invalid argument to -B: %s", arg+2);
        }
 -      else if (!prefixcmp(arg, "-M")) {
 +      else if (!prefixcmp(arg, "-M") || !prefixcmp(arg, "--detect-renames=") ||
 +               !strcmp(arg, "--detect-renames")) {
                if ((options->rename_score = diff_scoreopt_parse(arg)) == -1)
-                       return -1;
+                       return error("invalid argument to -M: %s", arg+2);
                options->detect_rename = DIFF_DETECT_RENAME;
        }
 -      else if (!prefixcmp(arg, "-C")) {
 +      else if (!prefixcmp(arg, "-C") || !prefixcmp(arg, "--detect-copies=") ||
 +               !strcmp(arg, "--detect-copies")) {
                if (options->detect_rename == DIFF_DETECT_COPY)
                        DIFF_OPT_SET(options, FIND_COPIES_HARDER);
                if ((options->rename_score = diff_scoreopt_parse(arg)) == -1)