[PATCH v5 0/1] cat-file: add mailmap subcommand to --batch-command

git-cat-file(1)'s --batch-command works with the --use-mailmap option, but this option needs to be set when the process is created. This means we cannot change this option mid-operation.

At GitLab, Gitaly keeps interacting with a long-lived git-cat-file process and it would be useful if --batch-command supported toggling mailmap dynamically on an existing process.

This patch adds a `mailmap` subcommand to --batch-command that accepts a boolean argument and toggles mailmap dynamically for subsequent commands.

The series is based on top of 5361983c07 (The 22nd batch, 2026-03-21).

CI: https://gitlab.com/gitlab-org/git/-/pipelines/2456596910

Changes in v5:
- Simplify documentation: remove the `;;` sub-list describing
  `true`/`false` effects and replace with a single sentence noting
  that mailmap data is read upon the first use and only once.
- Link to v4: https://lore.kernel.org/git/20260415150943.40493-1-siddharthasthana31@gmail.com/T/#m5226263dafcf5c774c080a6688e9af0f402003c0
- Link to v3: https://lore.kernel.org/git/xmqqv7dyoei6.fsf@gitster.g/T/#m0a109f3eb5129e619ecec5f2d58ead0c5a49a4f3
- Link to v2: https://lore.kernel.org/git/xmqqv7dyoei6.fsf@gitster.g/T/#m445eab3b309bded92d1b130d225b882c73988ff2
- Link to v1: https://public-inbox.org/git/a4ec7bfa-f16b-4505-9b37-d3dd137e93cb@gmail.com/T/#m5c62fb6ad0fbcc99a706dba4c78b66359c247acd

Thanks, Siddharth

---
Siddharth Asthana (1):
  cat-file: add mailmap subcommand to --batch-command

 Documentation/git-cat-file.adoc |   5 ++
 builtin/cat-file.c              |  37 ++++++++++++--
 t/t4203-mailmap.sh              | 105 ++++++++++++++++++++++++++++++++++++++++
 3 files changed, 143 insertions(+), 4 deletions(-)

Range-diff versus v4:

1:  25ebffe39e ! 1:  b4d6f08b43 cat-file: add mailmap subcommand to --batch-command
    @@ Documentation/git-cat-file.adoc: flush::
     +`mailmap (<bool>)`::
     +	Enable or disable mailmap for subsequent commands. The `<bool>`
     +	argument accepts the same boolean values as linkgit:git-config[1].
    -+	Possible effects are:
    -++
    -+`true`;;
    -+	Mailmap data is loaded on first use and kept in memory until the
    -+	process exits. Passing `true` again does not reload the data.
    -+`false`;;
    -+	Mailmap replacements are disabled for subsequent commands, but data
    -+	already loaded stays in memory.
    ++	The mailmap data is read upon the first use and only once.
      --
      +
      

base-commit: 5361983c075154725be47b65cca9a2421789e410