* Test suite: Honour DGIT_TEST_DEBUG=''.
* Print a supplementary message when push fails, giving advice to
the user about how to retry. Closes:#793144.
+ * Honour dgit-distros.DISTRO.cmd-CMD and .opts-CMD. Closes:#793427.
+ * Slurp in entire git config, for better performance.
+ * With -DDDD, print out all gitcfg references (copious!)
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