travis-ci: switch to Xcode 10.1 macOS image

diff --git a/Documentation/git-format-patch.txt b/Documentation/git-format-patch.txt
index 9b2e17215999cc56553ed3234e6084bc7cc8a580..27304428a12ce9d0ee46e10e3c63069b4677838a 100644 (file)
--- a/Documentation/git-format-patch.txt
+++ b/Documentation/git-format-patch.txt
@@ -241,7 +241,8 @@ feeding the result to `git send-email`.
 
 --range-diff=<previous>::
        As a reviewer aid, insert a range-diff (see linkgit:git-range-diff[1])
-       into the cover letter showing the differences between the previous
+       into the cover letter, or as commentary of the lone patch of a
+       1-patch series, showing the differences between the previous
        version of the patch series and the series currently being formatted.
        `previous` can be a single revision naming the tip of the previous
        series if it shares a common base with the series being formatted (for
@@ -249,6 +250,11 @@ feeding the result to `git send-email`.
        feature/v2`), or a revision range if the two versions of the series are
        disjoint (for example `git format-patch --cover-letter
        --range-diff=feature/v1~3..feature/v1 -3 feature/v2`).
++
+Note that diff options passed to the command affect how the primary
+product of `format-patch` is generated, and they are not passed to
+the underlying `range-diff` machinery used to generate the cover-letter
+material (this may change in the future).
 
 --creation-factor=<percent>::
        Used with `--range-diff`, tweak the heuristic which matches up commits