Description:
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When I try replace the dot by "_d_", preg_replace fails to replace all dots separated by only 1 character. Only One substitution by 2 is working.

Reproduce code:
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$texte = preg_replace("/(\w)\.(\w)/", "$1_d_$2", "a.b.c.d.e.f");


Expected result:
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The result is a_d_b.c_d_d.e_d_f

Actual result:
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The result should be a_d_b_d_c_d_d_d_e_d_f

On the other side, the replacement below works and gives the good result : aa_d_bb_d_cc_d_dd_d_ee_d_ff

$texte = preg_replace("/(\w)\.(\w)/", "$1_d_$2", "aa.bb.cc.dd.ee.ff");