merge(third_party/git): Merge squashed git subtree at v2.23.0 r/373

Merge commit '1b593e1ea4d2af0f6444d9a7788d5d99abd6fde5' as 'third_party/git'

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+git-blame(1)
+============
+
+NAME
+----
+git-blame - Show what revision and author last modified each line of a file
+
+SYNOPSIS
+--------
+[verse]
+'git blame' [-c] [-b] [-l] [--root] [-t] [-f] [-n] [-s] [-e] [-p] [-w] [--incremental]
+	    [-L <range>] [-S <revs-file>] [-M] [-C] [-C] [-C] [--since=<date>]
+	    [--ignore-rev <rev>] [--ignore-revs-file <file>]
+	    [--progress] [--abbrev=<n>] [<rev> | --contents <file> | --reverse <rev>..<rev>]
+	    [--] <file>
+
+DESCRIPTION
+-----------
+
+Annotates each line in the given file with information from the revision which
+last modified the line. Optionally, start annotating from the given revision.
+
+When specified one or more times, `-L` restricts annotation to the requested
+lines.
+
+The origin of lines is automatically followed across whole-file
+renames (currently there is no option to turn the rename-following
+off). To follow lines moved from one file to another, or to follow
+lines that were copied and pasted from another file, etc., see the
+`-C` and `-M` options.
+
+The report does not tell you anything about lines which have been deleted or
+replaced; you need to use a tool such as 'git diff' or the "pickaxe"
+interface briefly mentioned in the following paragraph.
+
+Apart from supporting file annotation, Git also supports searching the
+development history for when a code snippet occurred in a change. This makes it
+possible to track when a code snippet was added to a file, moved or copied
+between files, and eventually deleted or replaced. It works by searching for
+a text string in the diff. A small example of the pickaxe interface
+that searches for `blame_usage`:
+
+-----------------------------------------------------------------------------
+$ git log --pretty=oneline -S'blame_usage'
+5040f17eba15504bad66b14a645bddd9b015ebb7 blame -S <ancestry-file>
+ea4c7f9bf69e781dd0cd88d2bccb2bf5cc15c9a7 git-blame: Make the output
+-----------------------------------------------------------------------------
+
+OPTIONS
+-------
+include::blame-options.txt[]
+
+-c::
+	Use the same output mode as linkgit:git-annotate[1] (Default: off).
+
+--score-debug::
+	Include debugging information related to the movement of
+	lines between files (see `-C`) and lines moved within a
+	file (see `-M`).  The first number listed is the score.
+	This is the number of alphanumeric characters detected
+	as having been moved between or within files.  This must be above
+	a certain threshold for 'git blame' to consider those lines
+	of code to have been moved.
+
+-f::
+--show-name::
+	Show the filename in the original commit.  By default
+	the filename is shown if there is any line that came from a
+	file with a different name, due to rename detection.
+
+-n::
+--show-number::
+	Show the line number in the original commit (Default: off).
+
+-s::
+	Suppress the author name and timestamp from the output.
+
+-e::
+--show-email::
+	Show the author email instead of author name (Default: off).
+	This can also be controlled via the `blame.showEmail` config
+	option.
+
+-w::
+	Ignore whitespace when comparing the parent's version and
+	the child's to find where the lines came from.
+
+--abbrev=<n>::
+	Instead of using the default 7+1 hexadecimal digits as the
+	abbreviated object name, use <n>+1 digits. Note that 1 column
+	is used for a caret to mark the boundary commit.
+
+
+THE PORCELAIN FORMAT
+--------------------
+
+In this format, each line is output after a header; the
+header at the minimum has the first line which has:
+
+- 40-byte SHA-1 of the commit the line is attributed to;
+- the line number of the line in the original file;
+- the line number of the line in the final file;
+- on a line that starts a group of lines from a different
+  commit than the previous one, the number of lines in this
+  group.  On subsequent lines this field is absent.
+
+This header line is followed by the following information
+at least once for each commit:
+
+- the author name ("author"), email ("author-mail"), time
+  ("author-time"), and time zone ("author-tz"); similarly
+  for committer.
+- the filename in the commit that the line is attributed to.
+- the first line of the commit log message ("summary").
+
+The contents of the actual line is output after the above
+header, prefixed by a TAB. This is to allow adding more
+header elements later.
+
+The porcelain format generally suppresses commit information that has
+already been seen. For example, two lines that are blamed to the same
+commit will both be shown, but the details for that commit will be shown
+only once. This is more efficient, but may require more state be kept by
+the reader. The `--line-porcelain` option can be used to output full
+commit information for each line, allowing simpler (but less efficient)
+usage like:
+
+	# count the number of lines attributed to each author
+	git blame --line-porcelain file |
+	sed -n 's/^author //p' |
+	sort | uniq -c | sort -rn
+
+
+SPECIFYING RANGES
+-----------------
+
+Unlike 'git blame' and 'git annotate' in older versions of git, the extent
+of the annotation can be limited to both line ranges and revision
+ranges. The `-L` option, which limits annotation to a range of lines, may be
+specified multiple times.
+
+When you are interested in finding the origin for
+lines 40-60 for file `foo`, you can use the `-L` option like so
+(they mean the same thing -- both ask for 21 lines starting at
+line 40):
+
+	git blame -L 40,60 foo
+	git blame -L 40,+21 foo
+
+Also you can use a regular expression to specify the line range:
+
+	git blame -L '/^sub hello {/,/^}$/' foo
+
+which limits the annotation to the body of the `hello` subroutine.
+
+When you are not interested in changes older than version
+v2.6.18, or changes older than 3 weeks, you can use revision
+range specifiers  similar to 'git rev-list':
+
+	git blame v2.6.18.. -- foo
+	git blame --since=3.weeks -- foo
+
+When revision range specifiers are used to limit the annotation,
+lines that have not changed since the range boundary (either the
+commit v2.6.18 or the most recent commit that is more than 3
+weeks old in the above example) are blamed for that range
+boundary commit.
+
+A particularly useful way is to see if an added file has lines
+created by copy-and-paste from existing files.  Sometimes this
+indicates that the developer was being sloppy and did not
+refactor the code properly.  You can first find the commit that
+introduced the file with:
+
+	git log --diff-filter=A --pretty=short -- foo
+
+and then annotate the change between the commit and its
+parents, using `commit^!` notation:
+
+	git blame -C -C -f $commit^! -- foo
+
+
+INCREMENTAL OUTPUT
+------------------
+
+When called with `--incremental` option, the command outputs the
+result as it is built.  The output generally will talk about
+lines touched by more recent commits first (i.e. the lines will
+be annotated out of order) and is meant to be used by
+interactive viewers.
+
+The output format is similar to the Porcelain format, but it
+does not contain the actual lines from the file that is being
+annotated.
+
+. Each blame entry always starts with a line of:
+
+	<40-byte hex sha1> <sourceline> <resultline> <num_lines>
++
+Line numbers count from 1.
+
+. The first time that a commit shows up in the stream, it has various
+  other information about it printed out with a one-word tag at the
+  beginning of each line describing the extra commit information (author,
+  email, committer, dates, summary, etc.).
+
+. Unlike the Porcelain format, the filename information is always
+  given and terminates the entry:
+
+	"filename" <whitespace-quoted-filename-goes-here>
++
+and thus it is really quite easy to parse for some line- and word-oriented
+parser (which should be quite natural for most scripting languages).
++
+[NOTE]
+For people who do parsing: to make it more robust, just ignore any
+lines between the first and last one ("<sha1>" and "filename" lines)
+where you do not recognize the tag words (or care about that particular
+one) at the beginning of the "extended information" lines. That way, if
+there is ever added information (like the commit encoding or extended
+commit commentary), a blame viewer will not care.
+
+
+MAPPING AUTHORS
+---------------
+
+include::mailmap.txt[]
+
+
+SEE ALSO
+--------
+linkgit:git-annotate[1]
+
+GIT
+---
+Part of the linkgit:git[1] suite