Refer to a git commit by commit message headline

How can I refer to a git commit by the text / words in its commit message headline?

I want to avoid:

• Mouse copy / paste of a commit hash from git log
• Typing of commit hexadecimal digits

TL;DR:

Reference the most recent commit that matches <text>:

:/<text>, e.g. :/fix nasty bug

Reference the most recent commit reachable from <rev> that matches <text>

   <rev>^{/<text>}, e.g. HEAD^{/fix nasty bug}

Manual page entries

man gitrevisions says:

Reference the most recent commit reachable from <rev> that matches <text> :

   <rev>^{/<text>}, e.g. HEAD^{/fix nasty bug}
       A suffix ^ to a revision parameter, followed by a brace pair that
       contains a text led by a slash, is the same as the :/fix nasty bug
       syntax below except that it returns the youngest matching commit
       which is reachable from the <rev> before ^.

Reference the most recent commit anywhere that matches <text> :

   :/<text>, e.g. :/fix nasty bug
       A colon, followed by a slash, followed by a text, names a commit
       whose commit message matches the specified regular expression. This
       name returns the youngest matching commit which is reachable from any
       ref. The regular expression can match any part of the commit message.
       To match messages starting with a string, one can use e.g.  :/^foo.
       The special sequence :/!  is reserved for modifiers to what is
       matched.  :/!-foo performs a negative match, while :/!!foo matches a
       literal !  character, followed by foo. Any other sequence beginning
       with :/!  is reserved for now. Depending on the given text, the
       shell’s word splitting rules might require additional quoting.