absorb: preserve changesets which were already empty
Most commands in Mercurial (commit, rebase, absorb itself) don’t create empty
changesets or drop them if they become empty. If there’s a changeset that’s
empty, it must be a deliberate choice of the user. At least it shouldn’t be
absorb’s responsibility to prune them. The fact that changesets that became
empty during absorb are pruned, is unaffected by this.
This case was found while writing patches which make it possible to configure
absorb and rebase to not drop empty changesets. Even without having such config
set, I think it’s valuable to preserve changesets which were already empty.
#!/usr/bin/env python
#
# simple script to be used in hooks
#
# put something like this in the repo .hg/hgrc:
#
# [hooks]
# changegroup = python "$TESTDIR/printenv.py" <hookname> [exit] [output]
#
# - <hookname> is a mandatory argument (e.g. "changegroup")
# - [exit] is the exit code of the hook (default: 0)
# - [output] is the name of the output file (default: use sys.stdout)
# the file will be opened in append mode.
#
from __future__ import absolute_import
import argparse
import os
import sys
try:
import msvcrt
msvcrt.setmode(sys.stdin.fileno(), os.O_BINARY)
msvcrt.setmode(sys.stdout.fileno(), os.O_BINARY)
msvcrt.setmode(sys.stderr.fileno(), os.O_BINARY)
except ImportError:
pass
parser = argparse.ArgumentParser()
parser.add_argument("name", help="the hook name, used for display")
parser.add_argument(
"exitcode",
nargs="?",
default=0,
type=int,
help="the exit code for the hook",
)
parser.add_argument(
"out", nargs="?", default=None, help="where to write the output"
)
parser.add_argument(
"--line",
action="store_true",
help="print environment variables one per line instead of on a single line",
)
args = parser.parse_args()
if args.out is None:
out = sys.stdout
out = getattr(out, "buffer", out)
else:
out = open(args.out, "ab")
# variables with empty values may not exist on all platforms, filter
# them now for portability sake.
env = [(k, v) for k, v in os.environ.items() if k.startswith("HG_") and v]
env.sort()
out.write(b"%s hook: " % args.name.encode('ascii'))
if os.name == 'nt':
filter = lambda x: x.replace('\\', '/')
else:
filter = lambda x: x
vars = [
b"%s=%s" % (k.encode('ascii'), filter(v).encode('ascii')) for k, v in env
]
# Print variables on out
if not args.line:
out.write(b" ".join(vars))
else:
for var in vars:
out.write(var)
out.write(b"\n")
out.write(b"\n")
out.close()
sys.exit(args.exitcode)