gnulib-tool.py: Print warnings just like gnulib-tool.sh

[Bruno Haible]

This patch fixes a test suite error:

./test-cache-1-31.err tmp3074843-err differ: byte 1, line 1
--- ./test-cache-1-31.err       2024-04-12 00:02:39.013521019 +0200
+++ tmp3074843-err      2024-04-12 14:03:20.355689866 +0200
@@ -1 +1 @@
-gnulib-tool: warning: --po-domain has no effect without a --po-base option
+.../gnulib-tool.py: warning: --po-domain has no effect without a --po-base 
option
FAIL: gnulib-tool's error output has unexpected differences.
FAIL: test-cache-1-31.sh

There's no need to print the absolute file name of gnulib-tool here, at
warnings.


2024-04-12  Bruno Haible  <bruno@clisp.org>

        gnulib-tool.py: Print warnings just like gnulib-tool.sh.
        * pygnulib/main.py (main): When printing a warning, print just
        "gnulib-tool" instead of the absolute file name.

diff --git a/pygnulib/main.py b/pygnulib/main.py
index 5fec0ccc4a..9fadd4a4ea 100644
--- a/pygnulib/main.py
+++ b/pygnulib/main.py
@@ -709,7 +709,7 @@ def main() -> None:
         sys.stderr.write(message)
         sys.exit(1)
     if cmdargs.pobase == None and cmdargs.podomain != None:
-        message = '%s: warning: --po-domain has no effect without a --po-base 
option\n' % constants.APP['name']
+        message = 'gnulib-tool: warning: --po-domain has no effect without a 
--po-base option\n'
         sys.stderr.write(message)
     if mode != None and 'test' in mode and cmdargs.gnu_make:
         message = '%s: --gnu-make not supported when including tests\n' % 
constants.APP['name']
@@ -900,7 +900,7 @@ def main() -> None:
                         if module.getFiles():
                             print(name)
             else:
-                message = '%s: warning: file %s does not exist\n' % 
(constants.APP['name'], filename)
+                message = 'gnulib-tool: warning: file %s does not exist\n' % 
filename
                 sys.stderr.write(message)
 
     elif mode in ['import', 'add-import', 'remove-import', 'update']: