[PATCH 1/1] checkpatch: support "base-commit:" format

[John Hubbard <jhubbard@nvidia.com>]

In order to support the get-lore-mbox.py tool described in [1], I ran:

    git format-patch --base=<commit> --cover-letter <revrange>

...which generated a "base-commit: <commit-hash>" tag at the end of the
cover letter. However, checkpatch.pl generated an error upon encounting
"base-commit:" in the cover letter:

    "ERROR: Please use git commit description style..."

...because it found the "commit" keyword, and failed to recognize that
it was part of the "base-commit" phrase, and as such, should not be
subjected to the same commit description style rules.

Update checkpatch.pl to include a special case for "base-commit:", so
that that tag no longer generates a checkpatch error.

[1] https://lwn.net/Articles/811528/ "Better tools for kernel
    developers"

Cc: Andy Whitcroft <apw@canonical.com>
Cc: Joe Perches <joe@perches.com>
Cc: Konstantin Ryabitsev <konstantin@linuxfoundation.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
---
 scripts/checkpatch.pl | 1 +
 1 file changed, 1 insertion(+)

diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index a63380c6b0d2..f241865cedb3 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -2761,6 +2761,7 @@ sub process {
 
 # Check for git id commit length and improperly formed commit descriptions
 		if ($in_commit_log && !$commit_log_possible_stack_dump &&
+		    $line !~ /base-commit:/ &&
 		    $line !~ /^\s*(?:Link|Patchwork|http|https|BugLink):/i &&
 		    $line !~ /^This reverts commit [0-9a-f]{7,40}/ &&
 		    ($line =~ /\bcommit\s+[0-9a-f]{5,}\b/i ||
-- 
2.25.0